Journal ArticleDOI
Size-consistent wave functions for nondynamical correlation energy: The valence active space optimized orbital coupled-cluster doubles model
TLDR
In this paper, a hierarchy of feasible approximations to the nondynamical correlation energy based on coupled-cluster theory with variationally optimized orbitals is introduced, denoted as VOO-CCD, or VOD.Abstract:
The nondynamical correlation energy may be defined as the difference between full configuration interaction within the space of all valence orbitals and a single determinant of molecular orbitals (Hartree–Fock theory). In order to describe bond breaking, diradicals, and other electronic structure problems where Hartree–Fock theory fails, a reliable description of nondynamical correlation is essential as a starting point. Unfortunately, the exact calculation of nondynamical correlation energy, as defined above, involves computational complexity that grows exponentially with molecular size and is thus unfeasible beyond systems of just two or three heavy atoms. We introduce a new hierarchy of feasible approximations to the nondynamical correlation energy based on coupled-cluster theory with variationally optimized orbitals. The simplest member of this hierarchy involves connected double excitations within the variationally optimized valence active space and may be denoted as VOO-CCD, or VOD. VOO-CCD is size-consistent, has computational complexity proportional to the sixth power of molecule size, and is expected to accurately approximate the nondynamical correlation energy in such cases as single bond dissociation, diradicals, and anti-ferromagnetic coupling. We report details of our implementation of VOO-CCD and illustrate that it does indeed accurately recover the nondynamical correlation energy for challenging multireference problems such as the torsion of ethylene and chemical bond breaking.read more
Citations
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Advances in methods and algorithms in a modern quantum chemistry program package
Yihan Shao,Laszlo Fusti Molnar,Yousung Jung,Jörg Kussmann,Christian Ochsenfeld,Shawn T. Brown,Andrew T. B. Gilbert,Lyudmila V. Slipchenko,Sergey V. Levchenko,Darragh P. O’Neill,Robert A. DiStasio,Rohini C. Lochan,Tao Wang,Gregory J. O. Beran,Nicholas A. Besley,John M. Herbert,Ching Yeh Lin,Troy Van Voorhis,Siu Hung Chien,Alexander J. Sodt,Ryan P. Steele,Vitaly A. Rassolov,Paul E. Maslen,Prakashan P. Korambath,Ross D. Adamson,Brian Austin,Jon Baker,Edward F. C. Byrd,Holger Dachsel,Robert J. Doerksen,Andreas Dreuw,Barry D. Dunietz,Anthony D. Dutoi,Thomas R. Furlani,Steven R. Gwaltney,Andreas Heyden,So Hirata,Chao-Ping Hsu,Gary S. Kedziora,Rustam Z. Khalliulin,Phil Klunzinger,Aaron M. Lee,Michael S. Lee,WanZhen Liang,Itay Lotan,Nikhil Nair,Baron Peters,Emil Proynov,Piotr A. Pieniazek,Young Min Rhee,Jim Ritchie,Edina Rosta,C. David Sherrill,Andrew C. Simmonett,Joseph E. Subotnik,H. Lee Woodcock,Weimin Zhang,Alexis T. Bell,Arup K. Chakraborty,Daniel M. Chipman,Frerich J. Keil,Arieh Warshel,Warren J. Hehre,Henry F. Schaefer,Jing Kong,Anna I. Krylov,Peter Gill,Martin Head-Gordon,Martin Head-Gordon +68 more
TL;DR: Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces.
Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Journal ArticleDOI
Q-Chem 2.0: a high-performance ab initio electronic structure program package
Jing Kong,Christopher A. White,Christopher A. White,Anna I. Krylov,Anna I. Krylov,David Sherrill,David Sherrill,Ross D. Adamson,Thomas R. Furlani,Michael S. Lee,Aaron M. Lee,Steven R. Gwaltney,T. R. Adams,Christian Ochsenfeld,Andrew T. B. Gilbert,Gary S. Kedziora,Vitaly A. Rassolov,David Maurice,Nikhil Nair,Yihan Shao,Nicholas A. Besley,Paul E. Maslen,Paul E. Maslen,Jeremy P. Dombroski,Holger Daschel,Weimin Zhang,Prakashan P. Korambath,Jon Baker,Edward F. C. Byrd,Troy Van Voorhis,Manabu Oumi,So Hirata,Chao-Ping Hsu,Naoto Ishikawa,Jan Florián,Arieh Warshel,Benny G. Johnson,Peter Gill,Martin Head-Gordon,John A. Pople +39 more
TL;DR: This article contains brief descriptive discussions of the key physical features of all new algorithms and theoretical models, together with sample calculations that illustrate their performance.
Journal ArticleDOI
The spin–flip approach within time-dependent density functional theory: Theory and applications to diradicals
TL;DR: In this article, an extension of density functional theory to situations with significant nondynamical correlation is presented, based on the spin-flip approach which is capable of describing multireference wave functions within a single reference formalism as spin flipping, e.g., α→β, excitations from a high-spin (Ms=1) triplet reference state.
References
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Journal ArticleDOI
General atomic and molecular electronic structure system
Michael W. Schmidt,Kim K. Baldridge,Jerry A. Boatz,Steven T. Elbert,Mark S. Gordon,Jan H. Jensen,Shiro Koseki,Nikita Matsunaga,Kiet A. Nguyen,Shujun Su,Theresa L. Windus,Michel Dupuis,John A. Montgomery +12 more
TL;DR: A description of the ab initio quantum chemistry package GAMESS, which can be treated with wave functions ranging from the simplest closed‐shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication.
Journal ArticleDOI
Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields
TL;DR: In this article, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Journal ArticleDOI
A fifth-order perturbation comparison of electron correlation theories
TL;DR: In this paper, a new augmented version of coupled-cluster theory, denoted as CCSD(T), is proposed to remedy some of the deficiencies of previous augmented coupledcluster models.
Journal ArticleDOI
A full coupled‐cluster singles and doubles model: The inclusion of disconnected triples
TL;DR: The coupled cluster singles and doubles model (CCSD) as discussed by the authors is derived algebraically, presenting the full set of equations for a general reference function explicitly in spin-orbital form, and the computational implementation of the CCSD model, which involves cubic and quartic terms, is discussed and results are compared with full CI calculations for H2O and BeH2.
Journal ArticleDOI
Gaussian Basis Functions for Use in Molecular Calculations. III. Contraction of (10s6p) Atomic Basis Sets for the First‐Row Atoms
TL;DR: In this paper, the effects of contraction on the energies and one-electron properties of the water and nitrogen molecules were investigated, and the authors obtained principles which can be used to predict optimal contraction schemes for other systems without the necessity of such exhaustive calculations.