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Articles de revues sur le sujet "Molecular Energy - Dynamical Correlation"
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Feng, Hai-Ran, Xiang-Jia Meng, Peng Li et Yu-Jun Zheng. « Dynamical correlation between quantum entanglement and intramolecular energy in molecular vibrations : An algebraic approach ». Chinese Physics B 23, no 7 (juillet 2014) : 073301. http://dx.doi.org/10.1088/1674-1056/23/7/073301.
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HWA, RUDOLPH C. « GEOMETRICAL AND DYNAMICAL MULTIPLICITY FLUCTUATIONS IN HIGH-ENERGY NUCLEAR COLLISIONS ». International Journal of Modern Physics A 04, no 02 (janvier 1989) : 481–92. http://dx.doi.org/10.1142/s0217751x89000248.
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General properties of multiplicity fluctuation in high-energy nuclear collisions are considered. Quantities that can directly be related to the geometrical and dynamical sources of the fluctuation are identified. Formalism for treating impact-parameter selection is discussed. The connection with correlation is described. Recent data indicate the absence of any significant collective behavior in the current experiments at the SPS. The observable that can reveal the onset of such behavior is suggested.
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MAKRI, NANCY, AKIRA NAKAYAMA et NICHOLAS J. WRIGHT. « FORWARD-BACKWARD SEMICLASSICAL SIMULATION OF DYNAMICAL PROCESSES IN LIQUIDS ». Journal of Theoretical and Computational Chemistry 03, no 03 (septembre 2004) : 391–417. http://dx.doi.org/10.1142/s0219633604001112.
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Forward-backward semiclassical dynamics (FBSD) provides a practical methodology for including quantum mechanical effects in classical trajectory simulations of polyatomic systems. FBSD expressions for time-dependent expectation values or correlation functions take the form of phase space integrals with respect to trajectory initial conditions, weighted by the coherent state transform of a corrected density operator. Quantization through a discretized path integral representation of the Boltzmann operator ensures a proper treatment of zero point energy effects and of imaginary components in finite-temperature correlation functions, and extension to systems obeying Bose statistics is possible. Accelerated convergence is achieved via Monte Carlo or molecular dynamics sampling techniques and through the construction of improved imaginary time propagators. The accuracy of the methodology is demonstrated on several model systems, including models of Bose and Fermi particles. Applications to liquid argon, neon and para-hydrogen are presented.
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PAPA, M., et G. GIULIANI. « DYNAMICAL CORRELATIONS AND THE SYMMETRY INTERACTION ». International Journal of Modern Physics E 17, no 10 (novembre 2008) : 2320–25. http://dx.doi.org/10.1142/s0218301308011549.
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It is shown how many-body correlations involving the symmetry potential naturally arise in the molecular dynamics CoMD-II model. The effect of these correlations on the collision dynamics at the Fermi energies is briefly discussed. The comparison with predictions based on the density functional as obtained through EOS static calculations is also discussed.
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Yuan, Qiang, et Xi-Wen Hou. « Entropy, energy, and entanglement of localized states in bent triatomic molecules ». International Journal of Modern Physics B 31, no 12 (10 mai 2017) : 1750088. http://dx.doi.org/10.1142/s0217979217500886.
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The dynamics of quantum entropy, energy, and entanglement is studied for various initial states in an important spectroscopic Hamiltonian of bent triatomic molecules H2O, D2O, and H2S. The total quantum correlation is quantified in terms of the mutual information and the entanglement by the concurrence borrowed from the theory of quantum information. The Pauli entropy and the intramolecular energy usually used in the theory of molecules are calculated to establish a possible relationship between both theories. Sections of two quantities among these four quantities are introduced to visualize such relationship. Analytic and numerical simulations demonstrate that if an initial state is taken to be the stretch- or the bend-vibrationally localized state, the mutual information, the Pauli entropy, and the concurrence are dominant-positively correlated while they are dominantly anti-correlated with the interacting energy among three anharmonic vibrational modes. In particular, such correlation is more distinct for the localized state with high excitations in the bending mode. The nice quasi-periodicity of those quantities in D2O molecule reveals that this molecule prepared in the localized state in the stretching or the bending mode can be more appreciated for molecular quantum computation. However, the dynamical correlations of those quantities behave irregularly for the dislocalized states. Moreover, the hierarchy of the mutual information and the Pauli entropy is explicitly proved. Quantum entropy and energy in every vibrational mode are investigated. Thereby, the relation between bipartite and tripartite entanglements is discussed as well. Those are useful for the understanding of quantum correlations in high-dimensional states in polyatomic molecules from quantum information and intramolecular dynamics.
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Finn, Molly K., Remy Indebetouw, Kelsey E. Johnson, Allison H. Costa, C. H. Rosie Chen, Akiko Kawamura, Toshikazu Onishi et al. « Structural and Dynamical Analysis of the Quiescent Molecular Ridge in the Large Magellanic Cloud ». Astronomical Journal 164, no 2 (21 juillet 2022) : 64. http://dx.doi.org/10.3847/1538-3881/ac7aa1.
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Abstract We present a comparison of low-J 13CO and CS observations of four different regions in the LMC—the quiescent Molecular Ridge, 30 Doradus, N159, and N113, all at a resolution of ∼3 pc. The regions 30 Dor, N159, and N113 are actively forming massive stars, while the Molecular Ridge is forming almost no massive stars, despite its large reservoir of molecular gas and proximity to N159 and 30 Dor. We segment the emission from each region into hierarchical structures using dendrograms and analyze the sizes, masses, and line widths of these structures. We find that the Ridge has significantly lower kinetic energy at a given size scale and also lower surface densities than the other regions, resulting in higher virial parameters. This suggests that the Ridge is not forming massive stars as actively as the other regions because it has less dense gas and not because collapse is suppressed by excess kinetic energy. We also find that these physical conditions and energy balance vary significantly within the Ridge and that this variation appears only weakly correlated with distance from sites of massive-star formation such as R136 in 30 Dor, which is ∼1 kpc away. These variations also show only a weak correlation with local star formation activity within the clouds.
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Bonačič-Koutecký, Vlasta, Detlef Reichardt, Jiří Pittner, Piercarlo Fantucci et Jaroslav Koutecký. « Ab initio Molecular Dynamics for Determination of Structures of Alkali Metal Clusters and Their Temperatures Behavior ; An Example of Li9+ ». Collection of Czechoslovak Chemical Communications 63, no 9 (1998) : 1431–46. http://dx.doi.org/10.1135/cccc19981431.
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It will be shown that an ab initio molecular dynamics procedure based on gradient corrected density functionals for exchange and correlation and using a Gaussian atomic basis (AIMD-GDF) implemented for parallel processing represents a suitable tool for detailed and accurate investigation of structural and dynamical properties of small systems. Gradients of the Born-Oppenheimer ground state energy, obtained by iterative solution of the Kohn-Sham equations, are used to calculate the forces acting on atoms at each instantaneous configuration along trajectories generated by solving classical equations of motion. Dynamics of different isomers of the Li9+ cluster have been investigated as a function of excess energy. It is shown that different isomers, even those similar in energy, can exhibit different structural and dynamical behavior. The analysis of the simulations leads to the conclusion that structures with a central atom, in particular the centered antiprism of Li9+ exhibit concerted mobility of the peripheral atoms at relatively low excess energy. In contrast, compact tetrahedral type structures show much more rigid behavior at low excess energy. However, the former ones need larger excess of internal energy to undergo isomerizations to geometrically different structures than the latter ones. At the time scale of our simulations we found that for the intermediate excess energies it is "easier" to carry the cluster in the basin of the lowest energy isomer than in the reverse direction. It has been found that the liquid-like behavior in small Li clusters becomes apparent at relatively high temperature in spite of large mobility of their atoms.
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Kiselev, S. M. « Azimuthal multiparticle correlations in high-energy heavy-ion collisions in the molecular-dynamical model ». Physics Letters B 216, no 3-4 (janvier 1989) : 262–66. http://dx.doi.org/10.1016/0370-2693(89)91112-x.
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Comes, F. J. « Vector Correlations in Molecular Photofragmentations ». Laser Chemistry 11, no 3-4 (1 janvier 1991) : 151–56. http://dx.doi.org/10.1155/lc.11.151.
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Photofragmentation spectroscopy—the study of “half collisions” with polarized light of subdoppler line width—opens a window to look into the structure of molecules. The energy partitioning among the particular degrees of freedom of the products of the fragmentation reaction is described by the scalar properties, the direction and magnitude of a particular type of motion is described by the vector properties. The measurement of the scalar and vector properties allows a pictorial view of the intermediate state. The forces which make the fragments fly apart or rotate and vibrate can be “seen” from the line shapes. Information on the unstable intermediate state is gained from the stable fragments long after the dissociation of the parent molecule. In particular, information on the “lifetime” of the intermediate on a femtosecond time scale can be obtained.A number of molecules, mainly three and four atomic, have been studied by this technique. Hydrogen peroxide has shown up as a textbook example. A complete analysis was possible including not only correlation of different types of fragment motion but also a correlation of the two coincident particles formed from the same parent molecule. The experimental results are in full agreement with recent calculations of the dynamics of the fragmentation on newly obtained potential energy surfaces. Hydrogen peroxide shows a strong dependence of its potential energy on the dihedral angle in the two electronic states amenable to laser excitation. This experiment further demonstrates that an analysis is also possible if two states are excited simultaneously.Another good example is the fragmentation of hydrazoic acid for which also coincident pair correlation has been treated. Here again the results agree excellently with a qualitative picture which can be drawn from recently calculated ab initio potential energy surfaces. The HN3 example is much more complicated than the former one due to its higher structured upper potential energy surface. Strong rotational excitation is observed in the N2 fragment leaving the NH fragment rotationally cold.The treatment of vector correlations in molecular photofragmentation is a powerful tool for the study of the dynamics of molecular dissociation reactions.
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ZHANG, JINGBO, QICHUN FENG, LEI HUO et WEINING ZHANG. « TWO-PARTICLE CORRELATION IN HEAVY-ION COLLISIONS AT CSR ENERGY ». International Journal of Modern Physics E 16, no 07n08 (août 2007) : 2200–2204. http://dx.doi.org/10.1142/s0218301307007684.
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The predictions of the two-particle correlation by using the relativistic quantum molecular dynamics model are presented for the heavy-ion reactions at HIRFL-CSR energy. The two-proton correlation function with the final state interaction is calculated with the Lednicky code for the U + U collisions at beam energy 520 A MeV. Applying the imaging technique, the relationship between the freeze-out spatial distributions and the results of correlation femtoscopy is investigated. We find that one can reliably reconstruct the source functions from the two-particle correlation functions with ignoring the degree of space-momentum correlations at this energy. The results are useful to the designing the hadron detector at CSR.
Thèses sur le sujet "Molecular Energy - Dynamical Correlation"
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Martins, Marcio Marques. « Influência de parâmetros moleculares em funções de correlação temporal na dinâmica de solvatação mecânica ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6896.
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No presente trabalho descrevemos nossos resultados relativos à investigação da dinâmica de solvatação mecânica por meio de simulações por dinâmica molecular, respeitando o regime da resposta linear, em sistemas-modelo de argônio líquido com um soluto monoatômico ou diatômico dissolvido. Estudamos sistematicamente a influência dos parâmetros moleculares dos solutos (tamanho, polarizabilidade) e da densidade frente a vários modelos de solvatação. Funções de Correlação Temporal da Energia de Solvatação foram calculadas com relação à correlações de n-corpos (n = 2; 3) distinguindo interações repulsivas e atrativas para ambos os sistemas líquidos. Também obtivemos segundas derivadas temporais dessas funções referindo-se à parcelas translacionais, rotacionais e roto-translacionais na solução do diatômico. Encontramos que funções de correlação temporal coletivas podem ser razoavelmente bem aproximadas por correlações binárias a densidades baixas e, a densidades altas, correlações ternárias tornam-se mais importantes produzindo um descorrelacionamento mais rápido das funções coletivas devido a efeitos de cancelamento parciais. As funções de correlação para interações repulsivas e atrativas exibem comportamentos dinâmicos independentes do modelo de solvatação devido a fatores de escalonamento linear que afetam apenas as amplitudes das dessas funções de correlação temporal. Em geral, os sistemas com grau de liberdade rotacional apresentam tempos de correlação mais curtos para a dinâmica coletiva e tempos de correlação mais longos para as funções binárias e ternárias. Finalmente, esse estudo mostra que os sistemas contendo o diatômico relaxam-se predominantemente por mecanismos translacionais binários em modelos de solvatação envolvendo alterações apenas na polarizabilidade do soluto, e por mecanismos rotacionais atrativos binários em modelos envolvendo alterações no comprimento de ligação.In the present work, we describe our results concerning our molecular dynamics investigation of the mechanical solvation dynamics within the linear response regime in model systems composed by liquid argon with a monoatomic or diatomic solute. The effect of molecular parameters (size, polarizability) and density has been elucidated for various solvation models. Time Correlation Functions for the solvation energy were calculated and separated into n-body (n = 2; 3) contributions distinguishing repulsive and attractive interactions in both liquid systems. In addition, we computed second time derivatives of these functions in order to describe translational, rotational, and roto-translational portions in the solutions containing the diatomics. We found that collective time correlation functions are well described by binary correlations at low liquid densities and, at high densities, ternary correlations become more important producing faster decaying collective time correlation functions due to partial cancellation effects. The repulsive and attractive time correlation functions exhibit a dynamic behavior that is independent on the solvation model due to linear scaling factors that only affect the absolute amplitudes of these functions. In general, the systems involving a rotational degree of freedom furnish smaller correlation times for the collective solvation dynamics, but stronger correlated two-body and three-body terms. Finally, this study shows that the solvation dynamics for the solution containing the diatomics relaxes predominatly by binary translational mechanisms when solvation models involving changes only in the polarizability parameter are considered. Binary attractive rotational mechanism become important in models with changes in the bond length.
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Park, Chanbum. « Structure, dynamics and phase behavior of concentrated electrolytes for applications in energy storage devices ». Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22389.
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Diese Arbeit widmet sich der Untersuchung der dynamischen und strukturellen Eigenschaften sowie des Phasenverhaltens konzentrierter flüssiger Elektrolyte und ihrer Anwendung in Energiespeichern mittels Methoden der statistischen Mechanik und mithilfe atomistischer Molekulardynamik (MD) Simulationen.
Zuerst untersuchen wir die Struktur-Eigenschafts-Beziehungen in konzentrierten Elektrolytlösungen wie sie in Lithium-Schwefel (Li/S), durch wir ein MD Simulationsmodell repräsentativer state-of-the-art Elektrolyt-Systeme für Li/S-Batterien bestehend aus Polysulfiden, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) und LiNO 3 Elektrolyten mit jeweils unterschiedlichen Kettenlängen gemischt in organischen Lösungsmitteln aus 1,2-dimethoxyethane and 1,3-dioxolane erstellen.
Als Zweites befassen wir uns mit der Phasenseparation, die auftritt, wenn sich die physikalisch-chemischen Eigenschaften flüssiger Gemische voneinander unterscheiden. Diese Systeme bestehen üblicherweise aus einem konzentrierten anorganischen Salz und einer ionischen Flüssigkeit. In dieser Arbeit untersuchen wir eine Vielfalt von hochkonzentrierten wässrigen Elektrolytlösungen, die aus unterschiedlichen Zusammensetzungen von LiCl und LiTFSI bestehen. Daraufhin beantworten wir die Frage, wie unterschiedlich die Komponenten in der wässrigen Lösung gemischt sein sollten, damit eine solche flüssig-flüssig-Phasentrennung stattfinden kann.
Als letztes untersuchen wir die Ladungsabschirmung, die ein grundlegendes Phänomen ist, das die Struktur von Elektrolyten im Bulk und an Grenzflächen bestimmt. Wir haben in dieser Arbeit die Abschirmlängen für verschiedene Elektrolyte von niedrigen bis zu hohen Konzentrationen untersucht.Electrolytes can be found in numerous applications in daily life as well as in scientific research. The increases in demand for energy-storage systems, such as fuel cells, supercapacitors and batteries in which liquid electrolyte properties are critical for optimal function, draw critical attention to the physical and chemical properties of electrolytes. Those energy-storage devices contain intermediate or highly concentrated electrolytes where established theories, like the Debye-Hückel (DH) theory, are not applicable. Despite the efforts to describe the physical properties of intermediate or highly concentrated electrolytes, theoretical atomistic-level studies are still lacking. This thesis is devoted to critically investigate the transport/structural properties and a phase behavior of concentrated liquid electrolytes and their application in energy-storage devices, using statistical mechanics and atomistic molecular dynamics (MD) simulations. Firstly, we investigate the structure-property relationship in concentrated electrolyte solutions in next-generation lithium-sulfur (Li/S) batteries. Secondly, phase separation may exist if the physio-chemical properties of liquid mixtures are very different. Recently, the coexistence phase of two aqueous solutions of different salts at high concentrations was found, called aqueous biphasic systems. We explore a wide range of compositions at room temperature for highly concentrated aqueous electrolytes solutions that consist of LiCl and LiTFSI. Lastly, charge screening is a fundamental phenomenon that governs the structure of liquid electrolytes in the bulk and at interfaces. From the DH theory, the screening length is expected to be extremely small in highly concentrated electrolytes. Yet, recent experiments show unexpectedly high screening lengths in those. This intriguing phenomenon has prompted a new set of theoretical works. We investigate the screening lengths for various electrolytes from low to high concentrations.
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Voloshina, Elena, Denis Usvyat, Martin Schütz, Yuriy Dedkov et Beate Paulus. « On the physisorption of water on graphene : a CCSD(T) study ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138776.
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The electronic structure of the zero-gap two-dimensional graphene has a charge neutrality point exactly at the Fermi level that limits the practical application of this material. There are several ways to modify the Fermi-level-region of graphene, e.g. adsorption of graphene on different substrates or different molecules on its surface. In all cases the so-called dispersion or van der Waals interactions can play a crucial role in the mechanism, which describes the modification of electronic structure of graphene. The adsorption of water on graphene is not very accurately reproduced in the standard density functional theory (DFT) calculations and highly-accurate quantum-chemical treatments are required. A possibility to apply wavefunction-based methods to extended systems is the use of local correlation schemes. The adsorption energies obtained in the present work by means of CCSD(T) are much higher in magnitude than the values calculated with standard DFT functional although they agree that physisorption is observed. The obtained results are compared with the values available in the literature for binding of water on the graphene-like substratesDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Voloshina, Elena, Denis Usvyat, Martin Schütz, Yuriy Dedkov et Beate Paulus. « On the physisorption of water on graphene : a CCSD(T) study ». Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27779.
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The electronic structure of the zero-gap two-dimensional graphene has a charge neutrality point exactly at the Fermi level that limits the practical application of this material. There are several ways to modify the Fermi-level-region of graphene, e.g. adsorption of graphene on different substrates or different molecules on its surface. In all cases the so-called dispersion or van der Waals interactions can play a crucial role in the mechanism, which describes the modification of electronic structure of graphene. The adsorption of water on graphene is not very accurately reproduced in the standard density functional theory (DFT) calculations and highly-accurate quantum-chemical treatments are required. A possibility to apply wavefunction-based methods to extended systems is the use of local correlation schemes. The adsorption energies obtained in the present work by means of CCSD(T) are much higher in magnitude than the values calculated with standard DFT functional although they agree that physisorption is observed. The obtained results are compared with the values available in the literature for binding of water on the graphene-like substrates.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Suba, Slaven L. « Molecular correlation energy, density functional and quantum field approaches ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq30394.pdf.
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Hagy, Matthew Canby. « Dynamical simulation of structured colloidal particles ». Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50328.
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In this thesis, computer simulations are used to study the properties of new colloidal systems with structured interactions. These are pair interactions that include both attraction and repulsion. Structured colloids differ from conventional colloids in which the interactions between particles are either strictly attractive or strictly repulsive. It is anticipated that these novel interactions will give rise to new microscopic structure and dynamics and therefore new material properties. Three classes of structured interactions are considered: radially structured interactions with an energetic barrier to pair association, Janus surface patterns with two hemispheres of different surface charge, and striped surface patterns. New models are developed to capture the structured interactions of these novel colloid systems. Dynamical computer simulations of these models are performed to quantify the effects of structured interactions on colloid properties. The results show that structured interactions can lead to unexpected particle ordering and novel dynamics. For Janus and striped particles, the particle order can be captured with simpler isotropic coarse-grained models. This relates the static properties of these new colloids to conventional isotropically attractive colloids (e.g. depletion attracting colloids). In contrast, Janus and striped particles are found to have substantially slower dynamics than isotropically attractive colloids. This is explained by the observation of longer-duration reversible bonds between pairs of structured particles. Dynamical mapping methods are explored to relates the dynamics of these structured colloids to isotropically attractive colloids. These methods could also facilitate future nonequilibrium simulation of structured colloids with computationally efficient coarse-grained models.
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Pounds, Andrew J. « A generalized discrete dynamical search method for locating minimum energy molecular geometries ». Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/27144.
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Gordon, Sean Dennis Steven. « Two and three vector correlations in the rotationally inelastic scattering of state-selected NO(X) ». Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:ec0f133b-b2ef-482c-b90c-59fc313c8baa.
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In this thesis, an experimental and theoretical study of two and three vector correlations in the inelastic scattering of NO(X) with various rare gas atoms is presented. Vector correlations for a selection of rare gas systems were determined experimentally, and the observations were interpreted using a variety of classical and quantum mechanical models. The experiment is able to provide state-to-state resolution of the dynamics by means of an electrostatic hexapole and 1+1' resonantly enhanced multi-photon ionisation (REMPI). The simplest vector correlation of interest is the differential cross section (DCS), given by the k-k' correlation. The DCSs were determined experimentally for the NO(X)--Kr and NO(X)--Xe collision systems, both characterised by the relatively deep (≈140cm-1) attractive well and large extent of the attractive potential. The agreement between the experimental angular distributions and quantum mechanical DCS is very good for both systems. Classical calculations fail to correctly reproduce the form and magnitude of the DCS for either system, reflecting the inherently quantum mechanical nature of the collision. The classical calculations do however provide mechanistic insight into regions where the attractive part of the potential plays an important role in determining the dynamics. In order to investigate narrow angular features in the forward scattered direction, several experimental improvements to molecular beams and the detection ion-optic stack were made. Investigation into these structures revealed a strong contribution from molecular diffraction into the classical shadow of the NO(X), and the simple Fraunhofer model revealed a preference for scattering from an individual m→m' sub-state. Such measurements are in a region of the DCS where scattering is forbidden classically, and reveal the purely quantum nature of the collision interaction in the forward scattered direction. The low order k-k' correlation was then extended by using linearly or circularly polarised laser excitation. The interaction of the light with the molecular dipole allows the measurement of the k-k'-j' correlation. When linearly polarised light was used for the excitation laser, two of the rank two p{2}q(θ) renormalised polarisation dependent differential cross sections (PDDCSs), which describe rotational alignment, were obtained. With circularly polarised light, the rank one p{1}1-(θ) renormalised PDDCSs describing rotational orientation were determined. The collision induced alignment in NO(X)--Xe scattering was found to be well reproduced by classical and impulsive theories, highlighting the fact that the alignment is dominated by the propensity for the projection of j onto the kinematic apse to be conserved. The attractive part of the potential does augment the alignment renormalised PDDCSs, and this is most evident in states with strong features of the attractive part of the potential such as ℓ-type rainbows. The orientation is more strongly influenced by the attractive part of the potential and is also influenced by parity. In addition to the parity effect, there exist two limiting classical mechanisms which govern the orientation, one caused by attraction and the other repulsion. Finally, the bond axis of the NO(X) can be oriented by means of hexapole state selection combined with adiabatic orientation using a set of guiding rods. The integral steric effect, an r-k correlation, was measured for the NO(X)--Kr and NO(X)--Ar spin-orbit changing systems. There are large oscillations in the sign of the steric asymmetry which occur for scattering with the various rare gases. There are also large differences between the rare gases as the potentials become more attractive, and more isotropic. The steric asymmetry is well reproduced by quantum mechanics, however, a classical mechanism becomes dominant at high Δj.
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Lott, Geoffrey Adam 1980. « Probing local conformation and dynamics of molecular complexes using phase-selective fluorescence correlation and coherence spectroscopy ». Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10914.
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xv, 177 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.When two or more fluorescent chromophores are closely spaced in a macromolecular complex, dipolar coupling leads to delocalization of the excited states, forming excitons. The relative transition frequencies and magnitudes are sensitive to conformation, which can then be studied with optical spectroscopy. Non-invasive fluorescence spectroscopy techniques are useful tools for the study of dilute concentrations of such naturally fluorescent or fluorescently labeled biological systems. This dissertation presents two phase-selective fluorescence spectroscopy techniques for the study of dynamical processes in bio-molecular systems across a wide range of timescales. Polarization-modulated Fourier imaging correlation spectroscopy (PM-FICS) is a novel phase-selective fluorescence spectroscopy for simultaneous study of translational and conformational dynamics. We utilize modulated polarization and intensity gratings with phase-sensitive signal collection to monitor the collective fluctuations of an ensemble of fluorescent molecules. The translational and conformational dynamics can be separated and analyzed separately to generate 2D spectral densities and joint probability distributions. We present results of PM-FICS experiments on DsRed, a fluorescent protein complex. Detailed information on thermally driven dipole-coupled optical switching pathways is found, for which we propose a conformation transition mechanism. 2D phase-modulation electronic coherence spectroscopy is a third-order nonlinear spectroscopy that uses collinear pulse geometry and acousto-optic phase modulation to isolate rephasing and nonrephasing contributions to the collected fluorescence signal. We generate 2D spectra, from which we are able to determine relative dipole orientations, and therefore structural conformation, in addition to detailed coupling information. We present results of experiments on magnesium tetraphenylporphyrin dimers in lipid vesicle bilayers. The 2D spectra show clearly resolved diagonal and off-diagonal features, evidence of exciton behavior. The amplitudes of the distinct spectral features change on a femtosecond timescale, revealing information on time-dependent energy transfer dynamics. This dissertation includes co-authored and previously published material.
Committee in charge: Hailin Wang, Chairperson, Physics; Andrew Marcus, Advisor, Chemistry; Stephen Gregory, Member, Physics; Michael Raymer, Member, Physics; Marina Guenza, Outside Member, Chemistry
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Somasundaram, Theepaharan. « Simulation studies of molecular transport across the liquid-gas interface ». Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314223.
Texte intégralLivres sur le sujet "Molecular Energy - Dynamical Correlation"
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Hans-Beat, Bürgi, et Dunitz Jack D, dir. Structure correlation. Weinheim : VCH, 1994.
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United States. National Aeronautics and Space Administration., dir. [An investigation of the dynamical evolution of photoplanetary nebulae] : [annual status report, no. 1, 1 Nov. 1992-31 October, 1993]. [Washington, DC : National Aeronautics and Space Administration, 1994.
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Nitzan, Abraham. Chemical Dynamics in Condensed Phases. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780198529798.001.0001.
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This text provides a uniform and consistent approach to diversified problems encountered in the study of dynamical processes in condensed phase molecular systems. Given the broad interdisciplinary aspect of this subject, the book focuses on three themes: coverage of needed background material, in-depth introduction of methodologies, and analysis of several key applications. The uniform approach and common language used in all discussions help to develop general understanding and insight on condensed phases chemical dynamics. The applications discussed are among the most fundamental processes that underlie physical, chemical and biological phenomena in complex systems. The first part of the book starts with a general review of basic mathematical and physical methods (Chapter 1) and a few introductory chapters on quantum dynamics (Chapter 2), interaction of radiation and matter (Chapter 3) and basic properties of solids (chapter 4) and liquids (Chapter 5). In the second part the text embarks on a broad coverage of the main methodological approaches. The central role of classical and quantum time correlation functions is emphasized in Chapter 6. The presentation of dynamical phenomena in complex systems as stochastic processes is discussed in Chapters 7 and 8. The basic theory of quantum relaxation phenomena is developed in Chapter 9, and carried on in Chapter 10 which introduces the density operator, its quantum evolution in Liouville space, and the concept of reduced equation of motions. The methodological part concludes with a discussion of linear response theory in Chapter 11, and of the spin-boson model in chapter 12. The third part of the book applies the methodologies introduced earlier to several fundamental processes that underlie much of the dynamical behaviour of condensed phase molecular systems. Vibrational relaxation and vibrational energy transfer (Chapter 13), Barrier crossing and diffusion controlled reactions (Chapter 14), solvation dynamics (Chapter 15), electron transfer in bulk solvents (Chapter 16) and at electrodes/electrolyte and metal/molecule/metal junctions (Chapter 17), and several processes pertaining to molecular spectroscopy in condensed phases (Chapter 18) are the main subjects discussed in this part.
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Dunitz, Jack D., et Hans-Beat Bürgi. Structure Correlation. Wiley & Sons, Limited, John, 2008.
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Dunitz, Jack D., et Hans-Beat Bürgi. Structure Correlation. Wiley & Sons, Incorporated, John, 2008.
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Holubec, Viktor. Non-Equilibrium Energy Transformation Processes : Theoretical Description at the Level of Molecular Structures. Springer London, Limited, 2014.
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Non-equilibrium Energy Transformation Processes : Theoretical Description at the Level of Molecular Structures. Springer, 2014.
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Holubec, Viktor. Non-Equilibrium Energy Transformation Processes : Theoretical Description at the Level of Molecular Structures. Springer International Publishing AG, 2016.
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Thygesen, K. S., et A. Rubio. Correlated electron transport in molecular junctions. Sous la direction de A. V. Narlikar et Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.23.
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This article focuses on correlated electron transport in molecular junctions. More specifically, it considers how electronic correlation effects can be included in transport calculations using many-body perturbation theory within the Keldysh non-equilibrium Green’s function formalism. The article uses the GW self-energy method (G denotes the Green’s function and W is the screened interaction) which has been successfully applied to describe quasi-particle excitations in periodic solids. It begins by formulating the quantum-transport problem and introducing the non-equilibrium Green’s function formalism. It then derives an expression for the current within the NEGF formalism that holds for interactions in the central region. It also combines the GW scheme with a Wannier function basis set to study electron transport through two prototypical junctions: a benzene molecule coupled to featureless leads and a hydrogen molecule between two semi-infinite platinum chains. The results are analyzed using a generic two-level model of a molecular junction.
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Henriksen, Niels E., et Flemming Y. Hansen. Theories of Molecular Reaction Dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805014.001.0001.
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This book deals with a central topic at the interface of chemistry and physics—the understanding of how the transformation of matter takes place at the atomic level. Building on the laws of physics, the book focuses on the theoretical framework for predicting the outcome of chemical reactions. The style is highly systematic with attention to basic concepts and clarity of presentation. Molecular reaction dynamics is about the detailed atomic-level description of chemical reactions. Based on quantum mechanics and statistical mechanics or, as an approximation, classical mechanics, the dynamics of uni- and bimolecular elementary reactions are described. The first part of the book is on gas-phase dynamics and it features a detailed presentation of reaction cross-sections and their relation to a quasi-classical as well as a quantum mechanical description of the reaction dynamics on a potential energy surface. Direct approaches to the calculation of the rate constant that bypasses the detailed state-to-state reaction cross-sections are presented, including transition-state theory, which plays an important role in practice. The second part gives a comprehensive discussion of basic theories of reaction dynamics in condensed phases, including Kramers and Grote–Hynes theory for dynamical solvent effects. Examples and end-of-chapter problems are included in order to illustrate the theory and its connection to chemical problems. The book has ten appendices with useful details, for example, on adiabatic and non-adiabatic electron-nuclear dynamics, statistical mechanics including the Boltzmann distribution, quantum mechanics, stochastic dynamics and various coordinate transformations including normal-mode and Jacobi coordinates.
Chapitres de livres sur le sujet "Molecular Energy - Dynamical Correlation"
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Pulay, Péter, et Svein Saebø. « Strategies of Gradient Evaluation for Dynamical Electron Correlation ». Dans Geometrical Derivatives of Energy Surfaces and Molecular Properties, 95–107. Dordrecht : Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4584-5_7.
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Tsai, D. H., et S. F. Trevino. « Molecular Dynamical Studies of Energy Transport and Energy Sharing in Molecular Dissociation ». Dans Chemistry and Physics of Energetic Materials, 229–53. Dordrecht : Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2035-4_11.
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Grassi, A., G. M. Lombardo et G. Forte. « Simple Approaches to Calculate Correlation Energy in Polyatomic Molecular Systems ». Dans Correlations in Condensed Matter under Extreme Conditions, 279–87. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-53664-4_20.
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Micha, David A., et Eduardo F. Vilallonga. « The Collisional Time-Correlation Function Approach to Molecular Energy Transfer ». Dans Advances in Chemical Physics, 1–72. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470141427.ch1.
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Tripathi, A. N. « Chemical Binding and Electron Correlation Effect Studied by Inelastic X-Ray and High Energy Electron Spectroscopy ». Dans Trends in Atomic and Molecular Physics, 173–88. Boston, MA : Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-4259-9_11.
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Malrieu, Jean-Paul, Hongjiang Zhang et Jing Ma. « Is the dynamical polarization a significant part of the contribution of the triples to the correlation energy ? » Dans Vincenzo Barone, 135–41. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-34462-6_14.
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Perdew, John P., Lucian A. Constantin et Adrienn Ruzsinszky. « Energy Densities of Exchange and Correlation in the Slowly Varying Region of the Airy Gas ». Dans Advances in the Theory of Atomic and Molecular Systems, 297–310. Dordrecht : Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-2596-8_14.
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Dyall, Kenneth G., et Knut Faegri. « Correlation Methods ». Dans Introduction to Relativistic Quantum Chemistry. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195140866.003.0018.
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It is well known from nonrelativistic quantum chemistry that mean-field methods, such as the Hartree–Fock (HF) model, provide mainly qualitative insights into the electronic structure and bonding of molecules. To obtain reliable results of “chemical accuracy” usually requires models that go beyond the mean field and account for electron correlation. There is no reason to expect that the mean-field approach should perform significantly better in this respect for the relativistic case, and so we are led to develop schemes for introducing correlation into our models for relativistic quantum chemistry. There is no fundamental change in the concept of correlation between relativistic and nonrelativistic quantum chemistry: in both cases, correlation describes the difference between a mean-field description, which forms the reference state for the correlation method, and the exact description. We can also define dynamical and nondynamical correlation in both cases. There is in fact no formal difference between a nonrelativistic spin–orbital-based formalism and a relativistic spinor-based formalism. Thus we should be able to transfer most of the schemes for post-Hartree–Fock calculations to a relativistic post-Dirac–Hartree–Fock model. Several such schemes have been implemented and applied in a range of calculations. The main technical differences to consider are those arising from having to deal with integrals that are complex, and the need to replace algorithms that exploit the nonrelativistic spin symmetry by schemes that use time-reversal and double-group symmetry. In addition to these technical differences, however, there are differences of content between relativistic and nonrelativistic methods. The division between dynamical and nondynamical correlation is complicated by the presence of the spin–orbit interaction, which creates near-degeneracies that are not present in the nonrelativistic theory. The existence of the negative-energy states of relativistic theory raise the question of whether they should be included in the correlation treatment. The first two sections of this chapter are devoted to a discussion of these issues. The main challenges in the rest of this chapter are to handle the presence of complex integrals and to exploit time-reversal symmetry.
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Broman, Katheryn, Abigail U. Davis, Jordan May et Han-A. Park. « Lifestyle Factors, Mitochondrial Dynamics, and Neuroprotection ». Dans Neuroprotection - New Approaches and Prospects. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89416.
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The brain requires vast amounts of energy to carry out neurotransmission; indeed, it is responsible for approximately one-fifth of the body’s energy consumption. Therefore, in order to understand functions of brain cells under both normal and pathological conditions, it is critical to elucidate dynamics of intracellular energy. The mitochondrion is the key intercellular organelle that controls neuronal energy and survival. Numerous studies have reported a correlation between altered mitochondrial function and brain-associated diseases; thus mitochondria may serve as a promising target for treating these conditions. In this chapter, we will discuss the mechanisms of mitochondrial production, movement, and degradation in order to understand accessibility of energy during physiological and pathological conditions of the brain. While research targeting molecular dynamics is promising, translation into clinical relevance based on bench research is challenging. For these reasons, we will also summarize lifestyle factors, including interventions and chronic comorbidities that disrupt mitochondrial dynamics. By determining lifestyle factors that are readily accessible, we can propose a new viewpoint for a synergistic and translational approach for neuroprotection.
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Sethna, James P. « Correlations, response, and dissipation ». Dans Statistical Mechanics : Entropy, Order Parameters, and Complexity, 287–320. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198865247.003.0010.
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This chapter studies how systems wiggle, and how they respond and dissipate energy when kicked. The wiggling fluctuations are described using correlation functions, the yielding and dissipation are described using susceptibilities. The intricate relations between these quantities are explored using the Onsager regression hypothesis, fluctuation--response and fluctuation--dissipation theorems, and the Kramers--Krönig relation derived from causality (the response cannot precede the kick). The powerful tools of linear response theory described here are basic tools in our exploration of materials with scattering of sound, light, X-rays, and neutrons, and have become our primary description of the behavior of materials. Exercises describe applications to noise in nanojunctions, humans on subways, magnetic spins, molecular dynamics and Ising models, liquids and magnets, materials at critical points, and fluctuations in the early Universe.
Actes de conférences sur le sujet "Molecular Energy - Dynamical Correlation"
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Thomas, J. A., R. M. Iutzi et A. J. H. McGaughey. « Thermal Conductivity of Water/Carbon Nanotube Composite Systems : Insights From Molecular Dynamics Simulations ». Dans ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88029.
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The effective thermal conductivity of water/carbon nanotube (CNT) composite systems is predicted using molecular dynamics simulation. Both empty and water-filled CNTs with diameters ranging from 0.83 nm to 1.26 nm are considered. Using a direct application of the Fourier law, we explore the transition to diffusive phonon transport with increasing CNT length and identify the correlation between CNT diameter and fully-diffusive thermal conductivity. Using Green-Kubo linear response theory, we explore how the thermal conductivity of water inside CNT varies with tube diameter. We predict the effective thermal conductivity of the composite systems and examine how the phonon modes in the CNT are affected by interactions with the water molecules.
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Alimohammadi, Sepideh, Lesley James et Sohrab Zendehboudi. « A CPP Model to Asphaltene Precipitation ; Mapping p-p Interactions onto an Equation of State ». Dans SPE Canadian Energy Technology Conference. SPE, 2022. http://dx.doi.org/10.2118/208942-ms.
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Abstract Asphaltene may destabilize during the oil recovery, transportation, and processing and cause significant flow assurance problems that negatively affect the operational expenditures (OPEX). Modeling investigation of asphaltene precipitation and consequently deposition is a vital research component in flow assurance requiring the accurate description of the phenomena under various operational conditions. The structure of asphaltene molecules and the presence of heteroatoms play a significant role in the intermolecular forces and the mechanism of asphaltene aggregation. Nevertheless, the intermolecular forces, e.g., polar forces, and their addition to thermodynamic modeling of asphaltene phase behavior still need investigation. While the traditional equation of state (EoS), e.g., cubic EoS, does not provide any special treatment to polar energy, the π-π interaction and polar effect can be mapped into the EoS using a separate polar term. In this research, we use cubic EoS, cubic plus polar (CPP) EoS, and molecular dynamics (MD) (three different modeling approaches) to analyze the effect of asphaltene structure and operational conditions on the precipitation phenomenon. Comparing the error associated with correlation and prediction results of the models, we show that the CPP approach using optimization to tune parameters of the EoS is the most reliable approach, followed by CPP EoS using MD to find dipole moment for the aryl-linked core asphaltene structure. The CPP EoS and MD optimizing island structure for asphaltene is the third-best model, and SRK EoS is a less efficient approach. Considering the values for dipole moment and molecular weight of asphaltene, along with correlation and prediction ability of the techniques, it is revealed that polar forces can be considered in a separate term in addition to van der Waals force to increase the model efficiency. Moreover, the aryl structure with a 750 g/mol molecular weight and one/two thiophene/pyridine group is the most proper asphaltene structure.
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Nam, Woochul, et Bogdan I. Epureanu. « Collective Transport by Multiple Molecular Motors ». Dans ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71226.
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Kinesin is a processive molecular motor that transports various cellular cargoes by converting chemical energy into mechanical movements. Although the motion of a single molecule has been characterized in several studies, the dynamics of collective transports remains unresolved. Since the fluctuating load acting on each motor is an important factor in the collective transport, the relation between the varying force and the chemical reaction of kinesin is considered using a stochastic mechanistic model. Several metrics are developed to measure the correlation among the motion of the motors, the force distribution, and the power loss. It is shown that both large external load and stiff cargo linkers cause highly correlated motions of motors. However, these correlated motions do not lead to faster collective transport.
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Liang, Zhi, Hai-Lung Tsai et Lan Jiang. « Determination of Laser Absorption Coefficients of Gas Mixtures Using an Ab Initio MD Model ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41449.
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In an effort to study the laser induced dissociation of gas mixtures for an ongoing research project on diamond thin film coating using multiple lasers, it is necessary to determine the absorption coefficient of laser energy by CO2 gas. An ab initio molecular dynamics (AIMD) model is used to determine the laser absorption coefficient of CO2 gas as a function of laser wavelength and gas temperature. The translational, rotational, and vibration motions of molecules are all taken into account in our model. The intra-molecular potential energy is obtained by solving the Kohn-Sham equation. The Projector-Augmented Wave (PAW) exchange-correlation potential function is used in the ab initio calculation. Specific heat of the CO2 gas is also calculated. The calculated thermal properties of CO2 gas and the vibration spectrum of molecules are in good agreement with the experimental results. The calculated normalized absorption line shape CO2 gas is close to the experimental results.
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Jayadas, N. H., et K. Prabhakaran Nair. « Coconut Oil as Bio Lubricant : Study of the Anti-Wear Properties Using Quantum Chemical Calculations and Tribological Tests ». Dans World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63786.
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In this paper Spartan 02, a molecular dynamics software is used to analyze and predict the tribological properties of coconut oil in a qualitative manner on the basis of carbon chain length of the constituent fatty acids, their polarity (Net electrostatic charge, Qr) and the energies of the molecular orbitals EHOMO (Energy of the Highest Occupied Molecular Orbital) and ELUMO (Energy of the Lowest Unoccupied Molecular Orbital) and the enthalpies of formations (Hform) of the iron soaps of respective fatty acids. Tribological properties of the constituent fatty acids of coconut oil were evaluated using a four-ball tester as per ASTM D4172 method. The experimental results showed good correlation to the selected quantum chemical descriptors. The influence of an anti-wear additive on the tribological performance of coconut oil and the optimum additive concentration were also evaluated experimentally.
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Chen, Haibin, et Alan J. H. McGaughey. « Thermal Conductivity of Carbon Nanotubes With Defects ». Dans ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44173.
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The high thermal conductivities of carbon nanotubes (CNTs) measured experimentally and predicted from theory suggest that they are good candidates for next-generation thermal management materials. The quantities of CNTs needed in applications preclude the use of pristine products. Limited work, however, has been done to study thermal transport in CNTs with defects. In this paper, the thermal conductivities of pristine CNTs and CNTs with various defect types (adatoms, single vacancies, double vacancies, and Stone-Wales) are systematically predicted using molecular dynamics simulation and a direct application of the Fourier law. We investigate the correlation between the thermal conductivity and defect energy.
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Mukamel, Shaul, et Jasper Knoester. « Nonlinear Optical Susceptibilities ; Beyond the Local Field Approximation ». Dans Nonlinear Optical Properties of Materials. Washington, D.C. : Optica Publishing Group, 1988. http://dx.doi.org/10.1364/nlopm.1988.mb3.
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The Bloch-Maxwell equations are usually derived for isolated molecules interacting with an external electromagnetic field. This is justified in the limit of low molecular density, where intermolecular forces may be neglected. The problem which we address in this work is how to extend these equations in a systematic way to incorporate properly intermolecular forces. We thus develop a systematic microscopic basis for the calculation of nonlinear response functions and susceptibilities. Such a theory is essential for relating microscopic, single-molecule, polarizabilities to the macroscopic susceptibilities of optical materials. The local field approximation [1,2] is a mean-field procedure which is widely used in the calculation of molecular susceptibilities at finite densities, when intermolecular forces are important. The local field model provides a simple way to relate the polarizabilities of isolated molecules to the macroscopic susceptibilities. It is clear, however, that this procedure is not rigorous. It fails to take properly into account the correlated dynamics of the interacting many-body system, i.e., correlations among the molecules, as well as correlations between the molecules and the radiation field. Short-range forces (e.g., exchange) are totally neglected in this procedure. Moreover, even the dipoledipole forces are not fully taken into account. The resulting susceptibilities do not depend at all on the wavevectors (apart from the local field contribution) but just on the frequencies. This indicates that processes such as exciton migration and energy transfer and transport (e.g., the Forster transfer) are neglected in this procedure. Such processes are often added phenomelogically in order to interpret transient grating spectroscopy[3], which is a four-wave mixing technique that measures transport processes by following the wavevector dependence of the susceptibilities. The common derivation of the local field approximation cannot be extended to include these processes, since it is intrinsically a mean-field single molecule theory.
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Xiao, Yu, Jinliang Yuan et Bengt Sunde´n. « On Modeling Development of Microscopic Spatial Structure for the Catalyst Layer in a Proton Exchange Membrane Fuel Cell ». Dans ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54882.
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The typical catalyst layers (CLs) in proton exchange membrane fuel cells (PEMFCs) are fabricated as random heterogeneous composites to meet the multifunctional requirements of transport phenomena and electrochemical activity. The employment of Pt nano-particles, carbonaceous substrates and Nafion ionomers in CLs allows effective diffusion of hydrogen and oxygen, transport and phase change of water, migration and diffusion of protons, migration of electrons to and from the catalytic sites, which is accompanied by the oxidation of hydrogen in anodes and the generation of water and heat in cathodes. Based on the coarse-grained (CG) molecular dynamics method, a systematic technique is developed to provide insight into the self-organization phenomena and the microscopic spatial structure of the CLs. The formation of a CL is simulated by considering the interactions of the Pt clusters, carbon slabs, Nafion ionomers, hydronium ions and water. Meanwhile, the morphologies of Pt clusters are presented and compared with three cases. Moreover, the pair correlation functions (PCFs) are employed to predict the distributions and hydrophilic properties of the components. Finally, the TPB features are shown at the nano-scale level, which provides deeper view to understand the Pt utilization in the CLs.
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Miyazaki, Koji, Daisuke Nagai, Yohei Kido et Hiroshi Tsukamoto. « Numerical Calculation for Phonon Properties of a Nano-Porous Si ». Dans ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability. ASMEDC, 2009. http://dx.doi.org/10.1115/interpack2009-89118.
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We carried out molecular dynamics simulations (MD) of heat conduction in Si with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. The temperature is kept constant at 300K by velocity scaling. Periodic boundary conditions are applied in the x, y and z directions. Phonon dispersion curves are calculated by using the time-space 2D Fourier transform. The phonon group velocity is calculated from the slope of the dispersion curve. The velocity is reduced by nano-holes, even if those are random. Phonon mean free path can be evaluated from the width of dispersion curve, and the long waves are clearly scattered by nano-holes. Phonon density of states (DOS) is also calculated by the Fourier transform of a velocity correlation. The DOS of Si with periodic nano-holes are slightly smaller than that of a single crystal Si. In other words, the specific heat is reduced by periodic nano-holes due to the reduced phonon modes. We discuss the mechanism of the reduction of the thermal conductivity of nano-porous material on the atomic scale.
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Jo, Byeongnam, et Debjyoti Banerjee. « Interfacial Thermal Resistance Between a Carbon Nanoparticle and Molten Salt Eutectic : Effect of Material Properties, Particle Shapes and Sizes ». Dans ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44373.
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The aim of this study is to estimate the interfacial thermal resistance between a carbon nano-particle and alkali molten salt eutectics using molecular dynamics simulations. Additionally the effect of particle shapes and sizes on the interfacial thermal resistance was investigated using three different shapes of the carbon nanoparticles. Transient heat transfer simulation between a carbon particle and molecules of a molten salt was performed with the lumped capacitance method. A carbonate salt eutectic which consists of lithium carbonate (Li2CO3) and potassium carbonate (K2CO3) in 62:38 molar ratio was used as a solvent medium for the nanoparticles. Three carbon particles of a single walled carbon nanotube (SWNT), a fullerene (C60), and a graphite sheet were used to represent different shapes of cylinders, a spheres, and disks, respectively. The interfacial thermal resistance was determined by a correlation with a specific heat of the carbon particle, their surface area, and the time constant of decaying particle temperature. The results show the interfacial thermal resistance values are independent of the particle size for SWNT and graphite particles. For three carbon particles with a similar particle size, similar resistances were obtained in our simulations. The purpose of this study is to design and develop novel high-temperature Thermal Energy Storage (TES) materials in order to improve the operational efficiencies for harnessing solar thermal power at cheaper costs for Concentrated Solar Power (CSP) systems.
Rapports d'organisations sur le sujet "Molecular Energy - Dynamical Correlation"
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Pulay, Peter, et Jon Baker. Efficient Modeling of Large Molecules : Geometry Optimization Dynamics and Correlation Energy. Fort Belvoir, VA : Defense Technical Information Center, avril 2003. http://dx.doi.org/10.21236/ada416248.
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