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Автор: Grafiati
Опубліковано: 7 вересня 2023

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Статті в журналах з теми "Electronic Structure Calculations - Computational Methods"

1

Wang, Lin-Wang. "Novel Computational Methods for Nanostructure Electronic Structure Calculations." Annual Review of Physical Chemistry 61, no. 1 (March 2010): 19–39. http://dx.doi.org/10.1146/annurev.physchem.012809.103344.

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2

Zhang, Xin, Jinwei Zhu, Zaiwen Wen, and Aihui Zhou. "Gradient Type Optimization Methods For Electronic Structure Calculations." SIAM Journal on Scientific Computing 36, no. 3 (January 2014): C265—C289. http://dx.doi.org/10.1137/130932934.

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3

Richie, D. A., P. von Allmen, K. Hess, and Richard M. Martin. "Electronic Structure Calculations Using An Adaptive Wavelet Basis." VLSI Design 8, no. 1-4 (January 1, 1998): 159–63. http://dx.doi.org/10.1155/1998/62853.

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The use of a wavelet basis can lead to efficient methods for performing ab initio electronic structure calculations of inherently localized structures. In this work wavelets are used to construct an adaptive basis which is optimized dynamically throughout the calculation. The computational effort of such a method should scale linearly with the number of basis functions. The adaptive basis is tested for the case of bulk Si using only a local s-pseudopotential.
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4

Barettin, D., S. Madsen, B. Lassen, and M. Willatzen. "Computational Methods for Electromechanical Fields in Self-Assembled Quantum Dots." Communications in Computational Physics 11, no. 3 (March 2012): 797–830. http://dx.doi.org/10.4208/cicp.111110.110411a.

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AbstractA detailed comparison of continuum and valence force field strain calculations in quantum-dot structures is presented with particular emphasis to boundary conditions, their implementation in the finite-element method, and associated implications for electronic states. The first part of this work provides the equation framework for the elastic continuum model including piezoelectric effects in crystal structures as well as detailing the Keating model equations used in the atomistic valence force field calculations. Given the variety of possible structure shapes, a choice of pyramidal, spherical and cubic-dot shapes is made having in mind their pronounced shape differences and practical relevance. In this part boundary conditions are also considered; in particular the relevance of imposing different types of boundary conditions is highlighted and discussed.
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5

Zeng, Xiongzhi, Wei Hu, Xiao Zheng, Jin Zhao, Zhenyu Li, and Jinlong Yang. "Computational characterization of nanosystems." Chinese Journal of Chemical Physics 35, no. 1 (February 2022): 1–15. http://dx.doi.org/10.1063/1674-0068/cjcp2111233.

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Nanosystems play an important role in many applications. Due to their complexity, it is challenging to accurately characterize their structure and properties. An important means to reach such a goal is computational simulation, which is grounded on ab initio electronic structure calculations. Low scaling and accurate electronic-structure algorithms have been developed in recent years. Especially, the efficiency of hybrid density functional calculations for periodic systems has been significantly improved. With electronic structure information, simulation methods can be developed to directly obtain experimentally comparable data. For example, scanning tunneling microscopy images can be effectively simulated with advanced algorithms. When the system we are interested in is strongly coupled to environment, such as the Kondo effect, solving the hierarchical equations of motion turns out to be an effective way of computational characterization. Furthermore, the first principles simulation on the excited state dynamics rapidly emerges in recent years, and nonadiabatic molecular dynamics method plays an important role. For nanosystem involved chemical processes, such as graphene growth, multiscale simulation methods should be developed to characterize their atomic details. In this review, we review some recent progresses in methodology development for computational characterization of nanosystems. Advanced algorithms and software are essential for us to better understand of the nanoworld.
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6

Bligaard, Thomas, Martin P. Andersson, Karsten W. Jacobsen, Hans L. Skriver, Claus H. Christensen, and Jens K. Nørskov. "Electronic-Structure-Based Design of Ordered Alloys." MRS Bulletin 31, no. 12 (December 2006): 986–90. http://dx.doi.org/10.1557/mrs2006.225.

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AbstractWe describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational design of other materials as well. A central problem is how to treat the huge number of compounds that can be envisioned by varying the concentrations and the number of the elements involved. We discuss various strategies for approaching this problem and show how one strategy has led to the computational discovery of a promising catalytic metal alloy surface with high reactivity and low cost.
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7

Pototschnig, Johann V., Kenneth G. Dyall, Lucas Visscher, and André Severo Pereira Gomes. "Electronic spectra of ytterbium fluoride from relativistic electronic structure calculations." Physical Chemistry Chemical Physics 23, no. 39 (2021): 22330–43. http://dx.doi.org/10.1039/d1cp03701c.

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Potential energy curves for the YbF obtained by relativistic electronic structure methods are presented. Due to the difficulties of describing this system separate computations for open and closed f-shells were necessary.
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8

Stöhr, Martin, Troy Van Voorhis, and Alexandre Tkatchenko. "Theory and practice of modeling van der Waals interactions in electronic-structure calculations." Chemical Society Reviews 48, no. 15 (2019): 4118–54. http://dx.doi.org/10.1039/c9cs00060g.

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Opening the black box of van der Waals-inclusive electronic structure calculations: a tutorial-style introduction to van der Waals dispersion interactions, state-of-the-art methods in computational modeling and complementary experimental techniques.
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9

Breczko, T., V. Barkaline, and J. Tamuliene. "INVESTIGATION OF GEOMETRIC AND ELECTRONIC STRUCTURES OF HEUSLER ALLOYS: CUBIC AND TETRAGONAL LATTICES." EPH - International Journal of Applied Science 6, no. 1 (March 27, 2020): 1–5. http://dx.doi.org/10.53555/eijas.v6i1.102.

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Ni2MnGa and Co2MnGa compounds were investigated by using state-of-the-art computational ab-initio methods. The total energy calculations for the cubic and the tetrahedral structures, band structure together with suspensibility investigations were performed. The results of our investigations exhibited the dependence of magnetic properties of the compounds on their geometrical structure. The influence of Co and Ni on the magnetic properties of the compounds was disclosed, too.
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10

Fujiki, Ryo, Toru Matsui, Yasuteru Shigeta, Haruyuki Nakano, and Norio Yoshida. "Recent Developments of Computational Methods for pKa Prediction Based on Electronic Structure Theory with Solvation Models." J 4, no. 4 (December 10, 2021): 849–64. http://dx.doi.org/10.3390/j4040058.

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The protonation/deprotonation reaction is one of the most fundamental processes in solutions and biological systems. Compounds with dissociative functional groups change their charge states by protonation/deprotonation. This change not only significantly alters the physical properties of a compound itself, but also has a profound effect on the surrounding molecules. In this paper, we review our recent developments of the methods for predicting the Ka, the equilibrium constant for protonation reactions or acid dissociation reactions. The pKa, which is a logarithm of Ka, is proportional to the reaction Gibbs energy of the protonation reaction, and the reaction free energy can be determined by electronic structure calculations with solvation models. The charge of the compound changes before and after protonation; therefore, the solvent effect plays an important role in determining the reaction Gibbs energy. Here, we review two solvation models: the continuum model, and the integral equation theory of molecular liquids. Furthermore, the reaction Gibbs energy calculations for the protonation reactions require special attention to the handling of dissociated protons. An efficient method for handling the free energy of dissociated protons will also be reviewed.
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Дисертації з теми "Electronic Structure Calculations - Computational Methods"

1

Mak, Lora. "Computational approaches to protein structure and function : from 'Ab Initio' electronic structure calculations to 3D molecular structure description and comparison." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443086.

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Gorelov, Vitaly. "Quantum Monte Carlo methods for electronic structure calculations : application to hydrogen at extreme conditions." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF002.

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Le problème de la métallisation de l'hydrogène, posé il y a près de 80 ans, a été désigné comme la troisième question ouverte en physique du XXIe siècle. En effet, en raison de sa légèreté et de sa réactivité, les informations expérimentales sur l'hydrogène à haute pression sont limitées et extrêmement difficiles à obtenir. Il est donc essentiel de mettre au point des méthodes précises pour guider les expériences. Dans cette thèse, nous nous concentrons sur l'étude de la structure électronique, y compris les phénomènes d'état excité, en utilisant les techniques de Monte Carlo quantique (QMC). En particulier, nous développons une nouvelle méthode de calcul pour le gap accompagnée d'un traitement précis de l'erreur induit par la taille finie de la cellule de simulation. Nous établissons un lien formel entre l'erreur de la taille finie et la constante diélectrique du matériau. Avant d'étudier l'hydrogène, la nouvelle méthode est testée sur du silicium cristallin et du carbone de diamant, pour lesquels des informations expérimentales sur l'écart sont disponibles. Nos résultats montrent que le biais dû à la supercellule de taille finie peut être corrigé, de sorte que des valeurs précises dans la limite thermodynamique peuvent être obtenues pour les petites supercellules sans avoir besoin d'une extrapolation numérique. Comme l'hydrogène est un matériau très léger, les effets quantiques nucléaires sont importants. Une description précise des effets nucléaires peut être réalisée par la méthode de Monte Carlo à ions et électrons couplés (CEIMC), une méthode de simulation des premiers principes basée sur le QMC. Nous utilisons les résultats de la méthode CEIMC pour discuter les effets quantiques et thermiques des nuclei sur des propriétés électroniques. Nous introduisons une méthode formelle de traitement du gap électronique et de la structure des bandes à température finie dans l'approximation adiabatique et discutons des approximations qui doivent être faites. Nous proposons également une nouvelle méthode pour calculer des propriétés optiques à basse température, qui constituera une amélioration par rapport à l'approximation semi-classique couramment utilisée. Enfin, nous appliquons tout le développement méthodologique de cette thèse pour étudier la métallisation de l'hydrogène solide et liquide. Nous constatons que pour l'hydrogène moléculaire dans sa structure cristalline parfaite, le gap QMC est en accord avec les calculs précédents de GW. Le traitement des effets quantiques nucléaires entraîne une forte réduction du gap (2 eV). Selon la structure, le gap indirect fondamental se ferme entre 380 et 530 GPa pour les cristaux idéaux et 330-380 GPa pour les cristaux quantiques, ce qui dépend moins de la symétrie cristalline. Au-delà de cette pression, le système entre dans une phase de mauvais métal où la densité des états au niveau de Fermi augmente avec la pression jusqu'à 450-500 GPa lorsque l'écart direct se ferme. Notre travail soutient en partie l'interprétation des récentes expériences sur l'hydrogène à haute pression. Nous explorons également la possibilité d'utiliser une représentation multidéterminante des états excités pour modéliser les excitations neutres et calculer la conductivité via la formule de Kubo. Nous avons appliqué cette méthodologie à l'hydrogène cristallin idéal et limité au niveau de Monte Carlo variationnel de la théorie. Pour l'hydrogène liquide, la principale conclusion est que la fermeture du gap est continue et coïncide avec la transition de dissociation moléculaire. Nous avons été en mesure d'étalonner les fonctions de la théorie fonctionnelle de la densité (DFT) en nous basant sur la densité QMC des états. En utilisant les valeurs propres des calculs Kohn-Sham corrigé par QMC pour calculer les propriétés optiques dans le cadre de la théorie de Kubo-Greenwood , nous avons constaté que l'absorption optique théorique calculée précédemment s'est déplacée vers des énergies plus faibles
The hydrogen metallization problem posed almost 80 years ago, was named as the third open question in physics of the XXI century. Indeed, due to its lightness and reactivity, experimental information on high pressure hydrogen is limited and extremely difficult to obtain. Therefore, the development of accurate methods to guide experiments is essential. In this thesis, we focus on studying the electronic structure, including excited state phenomena, using quantum Monte Carlo (QMC) techniques. In particular, we develop a new method of computing energy gaps accompanied by an accurate treatment of the finite simulation cell error. We formally relate finite size error to the dielectric constant of the material. Before studying hydrogen, the new method is tested on crystalline silicon and carbon diamond, systems for which experimental information on the gap is available. Although finite-size corrected gap values for carbon and silicon are larger than the experimental ones, our results demonstrate that the bias due to the finite size supercell can be corrected for, so precise values in the thermodynamic limit can be obtained for small supercells without need for numerical extrapolation. As hydrogen is a very light material, the nuclear quantum effects are important. An accurate capturing of nuclear effects can be done within the Coupled Electron Ion Monte Carlo (CEIMC) method, a QMC-based first-principles simulation method. We use the results of CEIMC to discuss the thermal renormalization of electronic properties. We introduce a formal way of treating the electronic gap and band structure at a finite temperature within the adiabatic approximation and discuss the approximations that have to be made. We propose as well a novel way of renormalizing the optical properties at low temperature, which will be an improvement upon the commonly used semiclassical approximation. Finally, we apply all the methodological development of this thesis to study the metallization of solid and liquid hydrogen. We find that for ideal crystalline molecular hydrogen the QMC gap is in agreement with previous GW calculations. Treating nuclear zero point effects cause a large reduction in the gap (2 eV). Determining the crystalline structure of solid hydrogen is still an open problem. Depending on the structure, the fundamental indirect gap closes between 380 and 530 GPa for ideal crystals and 330–380 GPa for quantum crystals, which depends less on the crystalline symmetry. Beyond this pressure, the system enters into a bad metal phase where the density of states at the Fermi level increases with pressure up to 450–500 GPa when the direct gap closes. Our work partially supports the interpretation of recent experiments in high pressure hydrogen. However, the scenario where solid hydrogen metallization is accompanied by the structural change, for example, a molecular dissociation, can not be disproved. We also explore the possibility to use a multideterminant representation of excited states to model neutral excitations and compute the conductivity via the Kubo formula. We applied this methodology to ideal crystalline hydrogen and limited to the variational Monte Carlo level of the theory. For liquid hydrogen, the main finding is that the gap closure is continuous and coincides with the molecular dissociation transition. We were able to benchmark density functional theory (DFT) functionals based on the QMC density of states. When using the QMC renormalized Kohn-Sham eigenvalues to compute optical properties within the Kubo-Greenwood theory, we found that previously calculated theoretical optical absorption has a shift towards lower energies
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3

Richard, Ryan. "Increasing the computational efficiency of ab initio methods with generalized many-body expansions." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385570237.

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4

Laury, Marie L. "Accurate and Reliable Prediction of Energetic and Spectroscopic Properties Via Electronic Structure Methods." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc500071/.

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Computational chemistry has led to the greater understanding of the molecular world, from the interaction of molecules, to the composition of molecular species and materials. Of the families of computational chemistry approaches available, the main families of electronic structure methods that are capable of accurate and/or reliable predictions of energetic, structural, and spectroscopic properties are ab initio methods and density functional theory (DFT). The focus of this dissertation is to improve the accuracy of predictions and computational efficiency (with respect to memory, disk space, and computer processing time) of some computational chemistry methods, which, in turn, can extend the size of molecule that can be addressed, and, for other methods, DFT, in particular, gain greater insight into which DFT methods are more reliable than others. Much, though not all, of the focus of this dissertation is upon transition metal species – species for which much less method development has been targeted or insight about method performance has been well established. The ab initio approach that has been targeted in this work is the correlation consistent composite approach (ccCA), which has proven to be a robust, ab initio computational method for main group and first row transition metal-containing molecules yielding, on average, accurate thermodynamic properties, i.e., within 1 kcal/mol of experiment for main group species and within 3 kcal/mol of experiment for first row transition metal molecules. In order to make ccCA applicable to systems containing any element from the periodic table, development of the method for second row transition metals and heavier elements, including lower p-block (5p and 6p) elements was pursued. The resulting method, the relativistic pseudopotential variant of ccCA (rp-ccCA), and its application are detailed for second row transition metals and lower p-block elements. Because of the computational cost of ab initio methods, DFT is a popular choice for the study of transition metals. Despite this, the most reliable density functionals for the prediction of energetic properties (e.g. enthalpy of formation, ionization potential, electron affinity, dissociation energy) of transition metal species, have not been clearly identified. The examination of DFT performance for first and second row transition metal thermochemistry (i.e., enthalpies of formation) was conducted and density functionals for the study of these species were identified. And, finally, to address the accuracy of spectroscopic and energetic properties, improvements for a series of density functionals have been established. In both DFT and ab initio methods, the harmonic approximation is typically employed. This neglect of anharmonic effects, such as those related to vibrational properties (e.g. zero-point vibrational energies, thermal contributions to enthalpy and entropy) of molecules, generally results in computational predictions that are not in agreement with experiment. To correct for the neglect of anharmonicity, scale factors can be applied to these vibrational properties, resulting in better alignment with experimental observations. Scale factors for DFT in conjunction with both the correlation and polarization consistent basis sets have been developed in this work.
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5

Rajapakshe, Senanayake Asha. "ELECTRONIC STRUCTURE AND BONDING FACTORS OF TRANSITION METAL - PENTADIENYL AND (FLUOROALKYL)PHOSPHINE COMPLEXES: PHOTOELECTRON SPECTROSCOPY AND COMPUTATIONAL METHODS." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1220%5F1%5Fm.pdf&type=application/pdf.

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6

Becker, Caroline [Verfasser], and Rainer [Akademischer Betreuer] Böckmann. "Development of computational methods for the prediction of protein structure, protein binding, and mutational effects using free energy calculations / Caroline Becker. Gutachter: Rainer Böckmann." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1054331456/34.

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7

Dugan, Nazim. "Quantum Monte Carlo Methods For Fermionic Systems: Beyond The Fixed-node Approximation." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612256/index.pdf.

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Developments are made on the quantum Monte Carlo methods towards increasing the precision and the stability of the non fixed-node projector calculations of fermions. In the first part of the developments, the wavefunction correction scheme, which was developed to increase the precision of the diusion Monte Carlo (DMC) method, is applied to non fixed-node DMC to increase the precision of such fermion calculations which do not have nodal error. The benchmark calculations indicate a significant decrease of statistical error due to the usage of the correction scheme in such non fixed-node calculations. The second part of the developments is about the modifications of the wavefunction correction scheme for having a stable non fixed-node DMC algorithm for fermions. The minus signed walkers of the non fixed-node calculations are avoided by these modifications in the developed stable algorithm. However, the accuracy of the method decreases, especially for larger systems, as a result of the discussed modifications to overcome the sign instability.
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8

Flores, Livas José. "Computational and experimental studies of sp3-materials at high pressure." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10127.

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Nous présentons des études expérimentales et théoriques de disiliciures alcalino-terreux, le disilane (Si2H6) et du carbone à haute pression. Nous étudions les disiliciures et en particulier le cas d’une phase plane de BaSI2 qui a une structure hexagonale avec des liaisons sp3 entre les atomes de silicium. Cet environnement électronique conduit à un gaufrage de feuilles du silicium. Nous démontrons alors une amélioration de la température de transition supraconductrice de 6 à 8.9 K lorsque les couches de silicium s’aplanissent dans cette structure. Des calculs ab initio basés sur DFT ont guidé la recherche expérimentale et permettent d’expliquer comment les propriétés électroniques et des phonons sont fortement affectés par les fluctuations du flambage des plans de silicium. Nous avons aussi étudié les phases cristallines de disilane à très haute pression et une nouvelle phase métallique est proposé en utilisant les méthodes de prédiction de structure cristalline. Les températures de transition calculées donnant un supraconducteur autour de 20 K à 100 GPa. Ces valeurs sont significativement plus faibles comparées à celles avancées dans la littérature. Finalement, nous présentons des études de structures de carbone à haute pression à travers une recherche de structure systématique. Nous avons trouvé une nouvelle forme allotropique du carbone avec une symétrie Cmmm que nous appelons Z-carbone. Cette phase est prévue pour être plus stable que le graphite pour des pressions supérieures à 10 GPa. Des expériences et simulation de rayon-X et spectre Raman sugèrent l’existence de Z-carbone dans des micro-domaines de graphite sous pression
We present experimental and theoretical studies of sp3 materials, alkaline-earth-metal (AEM) disilicides, disilane (Si2H6) and carbon at high pressure. First, we study the AEM disilicides and in particular the case of a layered phase of BaSi2 which has an hexagonal structure with sp3 bonding of the silicon atoms. This electronic environment leads to a natural corrugated Si-sheets. Extensive ab initio calculations based on DFT guided the experimental research and permit explain how electronic and phonon properties are strongly affected by changes in the buckling of the silicon plans. We demonstrate experimentally and theoretically an enhancement of superconducting transition temperatures from 6 to 8.9 K when silicon planes flatten out in this structure. Second, we investigated the crystal phases of disilane at the megabar range of pressure. A novel metallic phase of disilane is proposed by using crystal structure prediction methods. The calculated transition temperatures yielding a superconducting Tc of around 20 K at 100 GPa and decreasing to 13 K at 220 GPa. These values are significantly smaller than previously predicted Tc’s and put serious drawbacks in the possibility of high-Tc superconductivity based on silicon-hydrogen systems. Third, we studied the sp3-carbon structures at high pressure through a systematic structure search. We found a new allotrope of carbon with Cmmm symmetry which we refer to as Z-carbon. This phase is predicted to be more stable than graphite for pressures above 10 GPa and is formed by sp3-bonds. Experimental and simulated XRD, Raman spectra suggest the existence of Z-carbon in micro-domains of graphite under pressure
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Cankurtaran, Burak O. "Linear-scaling techniques for first principles calculations of stationary and dynamic systems." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/24.

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First principles calculations can be a computationally intensive task when studying large systems. Linear-scaling methods must be employed to find the electronic structure of systems consisting of thousands of atoms and greater. The goal of this thesis is to combine the linear-scaling divide-and-conquer (D&C) method with the linear-scaling capabilities of the SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) density functional theory (DFT) methodology and present this union as a viable approach to large-scale first principles calculations. In particular, the density matrix version of the D&C method is implemented into the SIESTA package. This implementation can accommodate high quality calculations consisting of atom numbers in the tens of thousands using moderate computing resources. Low quality calculations have been tested up to half million atoms using reasonably sized computing resources.The D&C method is extended to better handle atomic dynamics simulations. First, by alleviating issues caused by discontinuities in the potential energy surface, with the application of a switching function on the Hamiltonian and overlap matrices. This allows for a smooth potential energy surface to be generated. The switching function has the additional benefit of accelerating the self-consistent field (SCF) process. Secondly, the D&C frozen density matrix (FDM) is modified to allow for improved charge transfer between the active and constrained regions of the system. This modification is found to reduce both the number of SCF iterations required for self-consistency and the number of relaxation steps in a local geometry optimisation. The D&C paradigm is applied to the real-time approach of time-dependent density functional theory (TDDFT). The method is tested on a linear alkane molecule with varying levels of success.Divergences in the induced dipole moment occur when the external excitation field is aligned parallel to the axis of the molecule. The method succeeds in producing accurate dipole moments when the external field is aligned perpendicular to the molecule. Various techniques are tested to improve the proposed method. Finally, the performance and effectiveness of the current D&C implementation is evaluated by studying three current systems. The first two systems consist of two different DNA sequences and the last system is the large ZIF-100 zeolitic imidazolate framework (ZIF).
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10

López, Ríos Pablo. "Backflow and pairing wave function for quantum Monte Carlo methods." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/288882.

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Quantum Monte Carlo (QMC) methods are a class of stochastic techniques that can be used to compute the properties of electronic systems accurately from first principles. This thesis is mainly concerned with the development of trial wave functions for QMC. An extension of the backflow transformation to inhomogeneous electronic systems is presented and applied to atoms, molecules and extended systems. The backflow transformation I have developed typically retrieves an additional 50% of the remaining correlation energy at the variational Monte Carlo level, and 30% at the diffusion Monte Carlo level; the number of parameters required to achieve a given fraction of the correlation energy does not appear to increase with system size. The expense incurred by the use of backflow transformations is investigated, and it is found to scale favourably with system size. Additionally, I propose a single wave function form for studying the electron-hole system which includes pairing effects and is capable of describing all of the relevant phases of this system. The effectiveness of this general wave function is demonstrated by applying it to a particular transition between two phases of the symmetric electron-hole bilayer, and it is found that using a single wave function form gives a more accurate physical description of the system than using a different wave function to describe each phase. Both of these developments are new, and they provide a powerful set of tools for designing accurate wave functions. Backflow transformations are particularly important for systems with repulsive interactions, while pairing wave functions are important for attractive interactions. It is possible to combine backflow and pairing to further increase the accuracy of the wave function. The wave function technology that I have developed should therefore be useful across a very wide range of problems.
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Книги з теми "Electronic Structure Calculations - Computational Methods"

1

Royal Society of Chemistry. Faraday Division., ed. Molecular electronic structure calculations: Methods and applications. London: Royal Society of Chemistry, 1985.

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2

1950-, Wilson S., ed. Methods in computational chemistry. New York: Plenum, 1992.

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1950-, Wilson S., ed. Methods in computational chemistry. New York: Plenum, 1988.

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4

1950-, Wilson S., ed. Methods in computational chemistry. New York: Plenum, 1992.

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5

1950-, Wilson S., ed. Methods in computational chemistry. New York: Plenum Press, 1987.

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6

Alkauskas, Audrius. Advanced calculations for defects in materials: Electronic structure methods. Weinheim: Wiley-VCH, 2011.

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7

AEleen, Frisch, and Gaussian Inc, eds. Exploring chemistry with electronic structure methods. 2nd ed. Pittsburgh, PA: Gaussian, Inc., 1996.

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8

Computational methods for large systems: Electronic structure approaches for biotechnology and nanotechnology. Hoboken, N.J: Wiley, 2011.

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9

1938-, Kumar Vijay, Andersen O. K, Mookerjee Abhijit 1946-, and Working Group on "Disordered Alloys" (1992 : ICTP, Trieste, Italy), eds. Lectures on Methods of electronic structure calculations: Proceedings of the Miniworkshop on "Methods of Electronic Structure Calculations" and Working Group on "Disordered Alloys" : ICTP, Trieste, Italy, 10 August-4 September 1992. Singapore: World Scientific, 1994.

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10

Olle, Eriksson, Andersson Per, Delin Anna, Grechnyev Oleksiy, Alouani Mebarek, and SpringerLink (Online service), eds. Full-Potential Electronic Structure Method: Energy and Force Calculations with Density Functional and Dynamical Mean Field Theory. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2010.

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Частини книг з теми "Electronic Structure Calculations - Computational Methods"

1

Fattebert, Jean-Luc. "Finite Difference Methods in Electronic Structure Calculations." In Encyclopedia of Applied and Computational Mathematics, 521–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-540-70529-1_249.

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2

Temmerman, W. M., Z. Szotek, H. Winter, and G. Y. Guo. "Computational Methods in Electronic Structure Calculations of Complex Solids." In Supercomputational Science, 287–317. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-5820-6_23.

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3

Kohn, Scott, John Weare, M. Elizabeth Ong, and Scott Baden. "Software Abstractions and Computational Issues in Parallel Structured Adaptive Mesh Methods for Electronic Structure Calculations." In Structured Adaptive Mesh Refinement (SAMR) Grid Methods, 75–95. New York, NY: Springer New York, 2000. http://dx.doi.org/10.1007/978-1-4612-1252-2_5.

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4

Rubensson, Emanuel H., Elias Rudberg, and Pawel Salek. "Methods for Hartree-Fock and Density Functional Theory Electronic Structure Calculations with Linearly Scaling Processor Time and Memory Usage." In Challenges and Advances in Computational Chemistry and Physics, 263–300. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-2853-2_12.

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5

Schulz, Hannes, and Andreas Görling. "Toward a Comprehensive Treatment of Temperature in Electronic Structure Calculations: Non-zero-Temperature Hartree-Fock and Exact-Exchange Kohn-Sham Methods." In Lecture Notes in Computational Science and Engineering, 87–121. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04912-0_4.

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Grant, Ian P. "Relativistic Atomic Structure Calculations." In Methods in Computational Chemistry, 1–71. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0711-2_1.

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Wilson, Stephen. "Relativistic Molecular Structure Calculations." In Methods in Computational Chemistry, 73–108. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0711-2_2.

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Pyykkö, Pekka. "Semiempirical Relativistic Molecular Structure Calculations." In Methods in Computational Chemistry, 137–226. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0711-2_4.

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Götz, Andreas W. "Overview of Electronic Structure Methods." In Electronic Structure Calculations on Graphics Processing Units, 39–66. Chichester, UK: John Wiley & Sons, Ltd, 2016. http://dx.doi.org/10.1002/9781118670712.ch3.

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10

Kais, S., and R. Bleil. "Dimensional Renormalization For Electronic Structure Calculations." In New Methods in Quantum Theory, 55–70. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0227-5_3.

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Тези доповідей конференцій з теми "Electronic Structure Calculations - Computational Methods"

1

Wang, Lin-Wang, George Maroulis, and Theodore E. Simos. "Linear Scaling Electronic Structure Calculations for Nanosystems with Tens of Thousands of Atoms." In COMPUTATIONAL METHODS IN SCIENCE AND ENGINEERING: Advances in Computational Science: Lectures presented at the International Conference on Computational Methods in Sciences and Engineering 2008 (ICCMSE 2008). AIP, 2009. http://dx.doi.org/10.1063/1.3225401.

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2

Guo, Qiong, Osama R. Bilal, and Mahmoud I. Hussein. "A Fast Method for Electronic Band Structure Calculations." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65681.

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Анотація:
Band structure calculation provides a basis for the study of thermal, optical and magnetic properties of crystals. The reduced Bloch mode expansion (RBME) method is a model reduction method in which a selected set of Bloch eigenvectors within the irreducible Brillouin zone at high symmetry points are used to expand the unit cell problem at hand. In this method, a major reduction in computational cost is achieved with minimum loss of accuracy. The method applies to both classical and ab inito band structure calculations of periodic media, and to any type of wave propagation problem: phononic, photonic, electronic, etc. In this work, the applicability of RBME in calculating the three-dimensional (3D) electronic band structure for crystal structures with different symmetries is demonstrated. Using the Kronig-Penney fixed potential, a high-symmetry cubic model and a low-symmetry triclinic model are considered. For both cases, the energy (eigenvalues) and wave functions (eigenvectors) demonstrate very good convergence performance with the number of expansion points.
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3

Manohar, Prashant Uday, Sourav Pal, George Maroulis, and Theodore E. Simos. "Constrained Variational Response to Fock-Space Multi-Reference Coupled-Cluster Theory: Formulation for Excited-State Electronic Structure Calculations and Some Pilot Applications." In Computational Methods in Science and Engineering. AIP, 2007. http://dx.doi.org/10.1063/1.2827017.

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4

Imachi, Hiroto, Seiya Yokoyama, Takami Kaji, Yukiya Abe, Tomofumi Tada, and Takeo Hoshi. "One-hundred-nm-scale electronic structure and transport calculations of organic polymers on the K computer." In INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2016 (ICCMSE 2016). Author(s), 2016. http://dx.doi.org/10.1063/1.4968636.

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5

Uğur, Şule, and Ahmet İyigör. "Calculations of structural, elastic, electronic, magnetic and phonon properties of FeNiMnAl by the first principles." In INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014). AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4897712.

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6

Teramae, Hiroyuki, and Yuriko Aoki. "Ab initio electronic structure calculation of polymononucleotide, a model of B-type DNA." In INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2018 (ICCMSE 2018). Author(s), 2018. http://dx.doi.org/10.1063/1.5079055.

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7

Teramae, Hiroyuki, and Yuriko Aoki. "An attempt at ab initio crystal orbital calculation of electronic structure of B-type model-DNA." In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2017 (ICCMSE-2017). Author(s), 2017. http://dx.doi.org/10.1063/1.5012302.

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8

Nascimento, Letícia A., Érica C. M. Nascimento, and João B. L. Martins. "Análise da estrutura eletrônica da tacrina e do neurotransmissor acetilcolina." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020150.

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Alzheimer's disease (AD) is a more common neurodegenerative process in the elderly population, characterized by a progressive loss of cognitive abilities, such as memory, language skills, disorientation, attention and depression. Cholinergic hypothesis therapy is the most successful approach for the symptomatic treatment of AD. The therapy consists in the use of drugs with inhibitory action against acetylcholinesterase (AChE) to avoid the decrease of acetylcholine concentration in synaptic clefts. Thus, this research aims to carry out the electronic and structural study of tacrina drug compared to the neurotransmitter acetylcholine, through computational calculations based on theoretical chemistry, using PM6 semi-empirical method jointly to DFT and MP2 methods.
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Gutman, Ivan. "TOPOLOGICAL INDICES – WHY AND HOW." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac,, 2021. http://dx.doi.org/10.46793/iccbi21.039g.

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By means of presently available high-level computational methods, based on quantum theory, it is possible to determine (predict) the main structural, electronic, energetic, geometric, and thermodynamic properties of a particular chemical species (usually a molecule), as well as the ways in which it changes in chemical reactions. When one needs to estimate such properties of thousands or millions of chemical species, such high-level calculations are no more feasible. Then simpler, but less accurate, approaches are necessary. One such approach utilized so-called “topological indices”. According to IUPAC ‘s definition [Pure Appl. Chem. 69 (1997) 1137]: A topological index is a numerical value associated with chemical constitution for correlation of chemical structure with various physical properties, chemical reactivity or biological activity. In the first part of the lecture, we show that „numerical values“are associated with many other complex phenomena, encountered in various areas of human activity, implying that „topological indices“ are used far beyond chemistry. Next, we discuss the number of possible chemical compounds. Simple calculation shows that the number of possible compounds zillion times exceeds the number of those that have been experimentally characterized. Even worse, in the entire Universe, there is not enough matter to make at least a single molecule of each possible compound. In the second part of the lecture, a few most popular topological indices will be presented, as well as the way in which these can be (and are being) applied in treating real-world problems.
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Tsuchida, E. "Practical Boundary Conditions for Electronic Structure Calculations." In 15th World Congress on Computational Mechanics (WCCM-XV) and 8th Asian Pacific Congress on Computational Mechanics (APCOM-VIII). CIMNE, 2022. http://dx.doi.org/10.23967/wccm-apcom.2022.092.

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Звіти організацій з теми "Electronic Structure Calculations - Computational Methods"

1

Langhoff, P. W., J. A. Boatz, R. J. Hinde, and J. A. Sheehy. Atomic Spectral Methods for Molecular Electronic Structure Calculations. Fort Belvoir, VA: Defense Technical Information Center, June 2004. http://dx.doi.org/10.21236/ada429238.

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EMBODIED CARBON CALCULATION AND ASSESSMENT FOR STEEL STRUCTURE PROJECT. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.299.

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Carbon emissions need to be reduced in order to achieve current sustainability and global climate emergency objectives. Structural engineers have control of over 50% of embodied carbon from the design of superstructures and substructures alone. Embodied carbon calculations do not only depend on the amount of structural materials, other factors such as transport, manufacturing and construction/installation needs to be considered, some of which are geographically specific. With significant focus on operation carbon on last few decades, embodied carbon is becoming equally important. Computational engineering technology with Grasshopper script has been developed to calculate embodied carbon for a steel structure project based on different structural scheme options. The related assessment has been provided to compare embodied carbon with different structural systems and representative Hong Kong Carbon benchmark database. In addition, different construction methods with supply chains also affect carbon emissions, the details have been shown in the paper.
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