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Methods of molecular quantum mechanics
01 Jan 1969-
TL;DR: In this article, a survey of many-electron wavefunctions spin and permutation symmetry is presented, including the Electron Distribution Self-Consistent Field Theory Valence Bond Theory Multiconfiguration SCF Theory Perturbation Theory and Diagram Techniques Large-Scale CI and the Unitary-Group Approach Small Terms in the Hamiltonian Static Properties Dynamic Properties Dynamic properties and Response Theory Propagator and Equation-of-Motion Methods Intermolecular Forces Appendixes: Atomic Orbitals Angular Momentum Symmetry and Group Concepts Relativistic
Abstract: Introductory Survey Mathematical Methods Many-Electron Wavefunctions Spin and Permutation Symmetry Digression: The Electron Distribution Self-Consistent Field Theory Valence Bond Theory Multiconfiguration SCF Theory Perturbation Theory and Diagram Techniques Large-Scale CI and the Unitary-Group Approach Small Terms in the Hamiltonian Static Properties Dynamic Properties and Response Theory Propagator and Equation-of-Motion Methods Intermolecular Forces Appendixes: Atomic Orbitals Angular Momentum Symmetry and Group Concepts Relativistic Terms in the Hamiltonian References Index
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TL;DR: Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn, a multifunctional program for wavefunction analysis.
Abstract: Multiwfn is a multifunctional program for wavefunction analysis. Its main functions are: (1) Calculating and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population analysis. (3) Bond order analysis. (4) Orbital composition analysis. (5) Plot density-of-states and spectrum. (6) Topology analysis for electron density. Some other useful utilities involved in quantum chemistry studies are also provided. The built-in graph module enables the results of wavefunction analysis to be plotted directly or exported to high-quality graphic file. The program interface is very user-friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open-source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com.
17,273 citations
Cites background from "Methods of molecular quantum mechan..."
...The function for r spin electrons is defined as follows ([23]):...
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...Hamiltonian kinetic energy density: The kinetic energy density is not uniquely defined,([11,23]) because the expected value of kinetic energy operator < w| (1/2)!(2)|w> can be recovered by integrating kinetic energy density from alternative definitions....
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TL;DR: In this paper, the three-parameter Lee-Yang-Parr (B3LYP) functional was used to compute low-lying electronic excitations of N2, ethylene, formaldehyde, pyridine and porphin.
5,087 citations
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TL;DR: In this paper, the Hartree-Fock parallel spin probability was used to identify localized electronic groups in atomic and molecular systems, which is completely independent of unitary orbital transformations.
Abstract: We introduce in this work a new approach to the identification of localized electronic groups in atomic and molecular systems. Our approach is based on local behavior of the Hartree–Fock parallel‐spin pair probability and is completely independent of unitary orbital transformations. We derive a simple ‘‘electron localization function’’ (ELF) which easily reveals atomic shell structure and core, binding, and lone electron pairs in simple molecular systems as well.
5,039 citations
TL;DR: In this article, potential-dependent transformations are used to transform the four-component Dirac Hamiltonian to effective two-component regular Hamiltonians, which already contain the most important relativistic effects, including spin-orbit coupling.
Abstract: In this paper, potential‐dependent transformations are used to transform the four‐component Dirac Hamiltonian to effective two‐component regular Hamiltonians. To zeroth order, the expansions give second order differential equations (just like the Schrodinger equation), which already contain the most important relativistic effects, including spin–orbit coupling. One of the zero order Hamiltonians is identical to the one obtained earlier by Chang, Pelissier, and Durand [Phys. Scr. 34, 394 (1986)]. Self‐consistent all‐electron and frozen‐core calculations are performed as well as first order perturbation calculations for the case of the uranium atom using these Hamiltonians. They give very accurate results, especially for the one‐electron energies and densities of the valence orbitals.
3,585 citations
TL;DR: A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided in this paper, covering approximately the last seven years, including developments in density functional theory and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces.
Abstract: A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Moller–Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr_2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.
2,396 citations