Дисертації з теми "Theoretical quantum chemistry"
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Rudberg, Elias. "Quantum Chemistry for Large Systems." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4561.
Повний текст джерелаLarsson, Per-Erik. "Modelling Chemical Reactions : Theoretical Investigations of Organic Rearrangement Reactions." Doctoral thesis, Uppsala University, Department of Quantum Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3475.
Повний текст джерелаChemical reactions are ubiquitous and very important for life and many other processes taking place on earth. In both theoretical and experimental studies of reactivity a transition state is often used to rationalise the outcome of such studies. The present thesis deals with calculations of transition states in radical cation rearrangements, and a principle of least motion study of the rearrangements in the barbaralyl cation.
In particular, alternative quadricyclane radical cation (Q∙+) rearrangements are extensively studied. The rearrangement of Q∙+ to norbornadiene is extremely facile and is often used as a prototype for one-electron oxidations. However, electron spin resonance (ESR) experiments show that there are additional cations formed from Q∙+. Two plausible paths for the rearrangement of Q∙+ to the 1,3,5-cycloheptatriene radical cation are located. The most favourable one is a multistep rearrangement with two shallow intermediates, which has a rate-limiting step of 16.5 kcal/mol. In addition, a special structure, the bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation, is identified on these alternative paths; and its computed ESR parameters agree excellently with the experimental spectrum assigned to another intermediate on this path. Moreover, this cation show a homoconjugative stabilization, which is uncommon for radical cations.
The bicyclopropylidene (BCP) radical cation undergoes ring opening to the tetramethyleneethane radical cation upon γ-irradiation of the neutral BCP. This rearrangement proceeds through a stepwise mechanism for the first ring opening with a 7.3 kcal/mol activation energy, while the second ring opening has no activation energy. The dominating reaction coordinate during each ring opening is an olefinic carbon rehybridization.
The principle of least motion is based on the idea that, on passing from reactant to product, the reaction path with the least nuclear change is the most likely. By using hyperspherical coordinates to define a distance measure between conformations on a potential energy surface, a possibility to interpret reaction paths in terms of distance arises. In applying this measure to the complex rearrangements of the barbaralyl cation, a correct ordering of the conformations on this surface is found.
Allis, Damian Gregory Spencer James T. Hudson Bruce S. "Computational quantum chemistry in initial designs and final analyses." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
Повний текст джерелаBassan, Arianna. "Theoretical studies of mononuclear non-heme iron active sites." Doctoral thesis, Stockholm : Fysikum, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-103.
Повний текст джерелаAi, Yuejie. "Theoretical studies on photophysics and photochemistry of DNA." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33531.
Повний текст джерелаQC 20110530
Wåhlin, Pernilla. "Theoretical Actinide Chemistry – Methods and Models." Doctoral thesis, Stockholms universitet, Fysikum, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54848.
Повний текст джерелаVelkov, Yasen. "Quantum nuclear dynamics in x-ray scattering and lasing." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9728.
Повний текст джерелаWright, Christopher James. "Theoretical studies of underscreened Kondo physics in quantum dots." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:62207edb-af3a-4340-a6f2-5264b1374a41.
Повний текст джерелаJayatilaka, Frederic William. "Theoretical studies of tunnel-coupled double quantum dots." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:756add23-aae6-4a71-a22b-087695bc600a.
Повний текст джерелаRubensson, Emanuel H. "Matrix Algebra for Quantum Chemistry." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9447.
Повний текст джерелаCampolieti, Giuseppe. "Quantum theoretical investigations of field modulation and spin dynamics in NMRNQR." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75955.
Повний текст джерелаHammar, Peter. "Quantum Chemical Studies of Enantioselective Organocatalytic Reactions." Licentiate thesis, Stockholm : Bioteknologi, Biotechnology, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4701.
Повний текст джерелаMintz, Benjamin Wilson Angela K. "Reducing the computational cost of Ab Initio methods." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9061.
Повний текст джерелаBorg, Anders. "Theoretical Photochemistry : Halogenated Arenes, Phytochromobilin, Ru(II)polypyridyl complexes and 6-4 photoadducts." Doctoral thesis, Uppsala universitet, Kvantkemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8469.
Повний текст джерелаRudberg, Elias. "Fock Matrix Construction for Large Systems." Licentiate thesis, Stockholm : Biotechnology (Institutionen för bioteknologi), KTH, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4247.
Повний текст джерелаGeorgieva, Polina. "Quantum Chemical Modeling of Enzymatic Methyl Transfer Reactions." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9695.
Повний текст джерелаHammar, Peter. "Quantum Chemical Studies of Mechanisms and Stereoselectivities of Organocatalytic Reactions." Doctoral thesis, KTH, Teoretisk kemi (stängd 20110512), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11616.
Повний текст джерелаQC 20100719
Ying, Fuming. "Application and development of quantum chemical methods. Density functional theory and valence bond theory." Licentiate thesis, KTH, Teoretisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25033.
Повний текст джерелаQC 20101006
Martín, Fernando J. "Theoretical synthesis of macromolecules from transferable functional groups /." *McMaster only, 2001.
Знайти повний текст джерелаMitchell, Andrew Keith. "Two-channel Kondo phases in coupled quantum dots." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:3d4e9d86-794c-441c-9d4b-20e6f1bd1de1.
Повний текст джерелаKirkbride, James M. R. "Coherent transient spectroscopy with quantum cascade lasers." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c7b897e5-052f-4c15-a3c9-f95ca3b56d70.
Повний текст джерелаPelmenschikov, Vladimir. "Theoretical Modeling of Enzyme Catalysis with Focus on Radical Chemistry." Doctoral thesis, Stockholm : Dept. of Physics, Stockholm university, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-513.
Повний текст джерелаJarrold, Thomas Furnley. "Single channel Kondo physics in triple quantum dots." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:e2772c4e-6c76-44b8-9c02-401d9f90b27f.
Повний текст джерелаChen, Shilu. "Quantum Chemical Modeling of Binuclear Zinc Enzymes." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9705.
Повний текст джерелаOlivares-Amaya, Roberto. "Quantum Chemistry in Nanoscale Environments: Insights on Surface-Enhanced Raman Scattering and Organic Photovoltaics." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10184.
Повний текст джерелаLao, Ka Un. "Accurate and Efficient Quantum Chemistry Calculations for Noncovalent Interactions in Many-Body Systems." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1457973344.
Повний текст джерелаSchwarz, Lauretta Rebecca. "Projector Quantum Monte Carlo methods for linear and non-linear wavefunction ansatzes." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267871.
Повний текст джерелаRemmert, Sarah M. "Reduced dimensionality quantum dynamics of chemical reactions." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:7f96405f-105c-4ca3-9b8a-06f77d84606a.
Повний текст джерелаMintz, Benjamin. "Reducing the Computational Cost of Ab Initio Methods." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9061/.
Повний текст джерелаEdwards, Luke J. "Highly efficient quantum spin dynamics simulation algorithms." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:3eec480e-5a3a-4197-a786-e6d42988d4a5.
Повний текст джерелаBiggs, Jason Daniel 1978. "Theoretical studies of the external vibrational control of electronic excitation transfer and its observation using polarization- and optical phase-sensitive ultrafast spectroscopy." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11074.
Повний текст джерелаOur theoretical studies involve the control of electronic energy transfer in molecular dimers through the preparation of specific vibrational coherences prior to electronic excitation. Our control strategy is based upon the fact that, following impulsive electronic excitation, nuclear motion acts to change the instantaneous energy difference between site-excited electronic states and thereby influences short-time electronic excitation transfer (EET). By inducing coherent intramolecular vibration in one of the chromophores prior to short-pulse electronic excitation, we exert external control over electronic dynamics. As a means to monitor this coherent control over EET, we propose using multidimensional wave-packet interferometry (md-WPI). Two pairs of polarized phase-related femtosecond pulses following the control pulse would generate superpositions of coherent nuclear wave packets in optically accessible electronic states. Interference contributions to the time- and frequency-integrated fluorescence signal due to overlaps among the superposed wave packets provide amplitude-level information on the nuclear and electronic dynamics. We test both the control strategy and its spectroscopic investigation by calculating pump-probe difference signals for various combinations of pulse polarizations. That signal is the limiting case of the control-influenced md-WPI signal in which the two pulses in the pump pulse-pair coincide, as do the two pulses in the probe pulse-pair. We present calculated pump-probe difference signals for a variety of systems including a simplified model of the covalent dimer dithia-anthracenophane (DTA) in which we treat only the weakly Franck-Condon active ν 12 anthracene vibration at 385 cm -1 . We further present calculated nl-WPI difference signals for an oriented DTA complex, which reveal amplitude-level dynamical information about the interaction of nuclear motion and electronic energy transfer. We also present pump-probe difference signals from a model system in which a CF 3 group, whose torsional angle is strongly Franck-Condon active, has been added to the anthracene monomers which make up DTA. We make use of electronic structure calculations to find the torsional potential of the monomer, from which we calculate the spectroscopic signals of the dimer. We show that a significant measure of control over short-time EET is achievable in this system. This dissertation includes previously published coauthored material.
Commitee in charge: Dr. Michael E. Kellman, Chair; Dr. Jeffrey A. Cina, Advisor; Dr. David R. Herrick; Dr. Andrew H. Marcus; Dr. Daniel A. Steck
Tucker, Adam Philip. "Local moment phases in quantum impurity problems." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:538d2d83-963e-4a51-81cd-4235e9761da4.
Повний текст джерелаPanesar, Kuldeep Singh. "Quantum molecular dynamics of guest molecules in supramolecular complexes." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10741/.
Повний текст джерелаLin, Na. "Theoretical Studies on Electronic and Vibrationally Resolved Multi-Photon Absorption and Dichroism." Doctoral thesis, Stockholm : Skolan för bioteknologi, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10212.
Повний текст джерелаRisko, Chad Michael. "Theoretical Evaluations of Electron-Transfer Processes in Organic Semiconductors." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7272.
Повний текст джерелаDourado, Augusto Gouvêa. "Uso de parâmetros teóricos de solutos em relações lineares de energia de solvatação." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-29112018-114651/.
Повний текст джерелаSemiempirical quantum theoretical parameters, obtained from PM3 geometry optimization method in gas-phase for a wide range of 700 solutes, were used to correlate experimental partition coeficients (log Poct; log Pc16 and log Pcyc), bearing as reference the LSER with experimentally derived parameters: Hydrogen bond acidity (Σα2), basicity (Σβ2) , and dipolarity/polarizability (π2); excess molar refraction and characteristic volume (Vx). Theoretical quantities tested includes: HOMO and LUMO energies; class IV, CM1 model atomic partial charges (q+ and Ιq-Ι) and dipole moment (µ); Famini\'s polarizability index (πF); and Vx. Those quantum derived quantities can successfully be used, jointly with Vx, to correlate log P values in the LSER approach. For most of the considered solutes, electrostatic quantities q+, Ιq-Ι and µ describes fairly well Hydrogen bond acidity, basicity and dipolarity terms, but do not describe hydrogen bond terms for solutes with more than one relevant positive or negative centers, like hydroquinone, nor solutes like 2-nitrophenol wich forms intramolecular hydrogen bond when in condensed phases. LSER with those theoretical parameters for log Poct, log Pc16 and log Pcic are chemically consistent. Atomic partial charges, widelly used to describe compounds and functional group reactivity in a qualitative way, can be used as a quantitative descriptor of molecular interactions in solubility, the first step wich drive a lot of chemical reactions.
Rodrigues, André Luis Gois. "Estudo Teórico da Espécie BeMg." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-21092018-100103/.
Повний текст джерелаThe first theoretical description of BeMg (using the SCF, CCD, and CEPA methods) was done by Chiles and Dykstra in 1982, when it was proposed that its electronic structure would be intermediate to Be2 and Mg2. In 1994, Boldyrev et al., using the QCISD method and 6 - 311+G* basis sets, presented other results on this diatomic species. To the best of our knowledge, there are no other study about this diatomic species. However, due to the nature of the atoms involved, it is necessary to employ more sophisticated theoretical methods to describe BeMg accurately. In this study, potential energy curves for the lowest-lying electronic states correlating with the first four dissociation channels were determined using the cc-p VQZ basis sets and CASSCF /MRCI wave functions. All valence orbitals plus one set of s and p correlating functions were included in the active space. A whole set of spectroscopic constants completes the characterization of each state. In its ground state (X1Σ+) BeMg is weakly bond (De = 0.05 eV), and consequently has a long internuclear equilibrium distance (Re = 3.30 Å, we = 44.2cm-1). It is interesting to note that in previous theoretical works, the internuclear equilibrium distance was calculated to be around 4.5 Å and 5.1 Å. The first two excited states are an a3II (Re = 2.416 Å, Te= 11029 cm-1) and a b3Σ+ (Re = 2.578 Å, Te= 11058 cm-1), with the same dissociation energy, 1.28 eV.
Lange, Adrian W. "Multi-layer Methods for Quantum Chemistry in the Condensed Phase: Combining Density Functional Theory, Molecular Mechanics, and Continuum Solvation Models." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1329752615.
Повний текст джерелаSinnokrot, Mutasem Omar. "Theoretical Investigations of pi-pi Interactions and Their Role in Molecular Recognition." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5019.
Повний текст джерелаGoh, Kelvin S. K. "Spectroscopic investigation of the quantum dynamics of small molecules encapsulated inside fullerene cages." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28849/.
Повний текст джерелаClark, Craig R. "Sympathetic heating and cooling of trapped atomic and molecular ions." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43757.
Повний текст джерелаFilho, Antonio Gustavo Sampaio de Oliveira. "Estudo teórico da reação O(3P) + HBr: superfícies de energia potencial, cinética e dinâmica." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-23042013-093150/.
Повний текст джерелаIn this work, the O(3P) + HBr → OH + Br reaction, which is relevant to atmospheric chemistry, specially for the catalytic ozone depletion, was studied using high-level ab initio potential energy surfaces. We constructed surfaces for the 3A\" and 3A\' electronic states, based on the many-body expansion, with the two-body potentials adjusted by the switched-MLJ function and the three-body potentials interpolated using the RKHS method. The ab initio points were calculated at the MRCISD+Q/CBS+SO level of theory. The main features of the 3A\" are the presence of two van der Waals minima, at the entrance and exit channels, and a transition state with a barrier height of 5.01 kcal mol-1. The 3A\' PES has a linear transition state at 6.45 kcal mol-1. We obtained the enthalpy of reaction, at 0 K, of -15.7 kcal mol-1, in close agreement with the experimental value of -15.14 kcal mol-1. Rate constants, in the temperature range from 200 to 1000 K, were calculated using the variational transition state theory with contributions of multidimensional tunneling (ICVT/µOMT) and also a quantum reactive scattering approach (QM/JS). Their values are in fair agreement with the experimental data in the literature in the whole temperature range available: from 221 to 554 K for the O + HBr reaction, and from 295 to 419 K for the O + DBr reaction. At 298 K, the calculated rate constants, in cm3 molecule-1 s-1, for the O + HBr reaction are 3.62·10-14 (ICVT/µOMT) and 3.35·10-14 (QM/JS); and the experimental value is 3.78·10-14. The quality of these results reinforces our confidence in the procedures and approximations used, leading to the possibility of high-level characterization of a variety of gas phase reactions.
Kinal, Armagan. "Theoretical Investigation Of Unimolecular Reactions Of Cyclic C5h6 Compounds By Ab Initio Quantum Chemical Methods." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605124/index.pdf.
Повний текст джерела) for the ring opening of B1 was calculated by the CR-CCSD(T) method to be 25.2 kcal/mol, in good agreement with experiment. Furthermore, the DH0¹
for the ring opening of T1 was obtained by the CR-CCSD(T) method to be 48.2 kcal/mol. The self-conversion of M1 via 1,5-hydrogen shift is a facile and concerted reaction with aromatic TS. The DH0¹
estimations of B3LYP and CC methods are 25.24 and 28.78 kcal/mol, respectively. For 1,2-hydrogen shift reactions of cyclopent-3-enylidene (M4) and cyclopenten-2-ylidene (M5), the single point CC calculations predicted the DH0¹
values of 3.13 and 10.12 kcal/mol, as well as, the DH0 values of -71.28 and -64.05 kcal/mol, respectively. The reason of M5 being more stable than M4 is due to the conjugation of the carbene carbon and the double bond in M5. The reaction path of cyclobutylidene methylene to cyclopentyne rearrangement is found to be rather shallow. The DH0¹
and DH0 values predicted by the RCCSD(T) method to be 3.65 and -5.72 kcal/mol, respectively. Finally, triplet state isomerization of bicyclo[2.1.0]pent-5-ylidene to cyclopenta-1,2-diene, as well as, its parent reaction, cyclopropylidene to 1,2-propadiene were investigated at several levels of theory including DFT, CASSCF and CC methods. The UCCSD(T) method estimated a moderate barrier whose value is 8.12 kcal/mol for the isomerization of 3B5 with the reaction enthalpy of -44.63 kcal/mol.
Hohenstein, Edward G. "Implementation and applications of density-fitted symmetry-adapted perturbation theory." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42699.
Повний текст джерелаEriksson, Martin. "Photoluminescence Characteristics of III-Nitride Quantum Dots and Films." Doctoral thesis, Linköpings universitet, Halvledarmaterial, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139766.
Повний текст джерелаWalker, Richard James. "Quantum cascade laser spectroscopy : developments and applications." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:5021ac50-c69d-4a1d-8071-e59ffed9fcb8.
Повний текст джерелаEngberg, André. "Exploiting excited-state aromaticity for the design of efficient molecular motors : A quantum chemical study." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-162675.
Повний текст джерелаTemelso, Berhane. "Computation of Molecular Properties at the Ab Initio Limit." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14638.
Повний текст джерелаLópez, José G. "Theoretical studies of the dynamics and spectroscopy of weakly bound systems." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1127220592.
Повний текст джерелаWalker, Alice Rachel. "Computational Simulations of Cancer and Disease-Related Enzymatic Systems Using Molecular Dynamics and Combined Quantum Methods." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157647/.
Повний текст джерела