Journal ArticleDOI
Efficient Structure Optimization with Second-Order Many-Body Perturbation Theory: The RIJCOSX-MP2 Method.
Simone Kossmann,Frank Neese +1 more
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TLDR
The application of the RIJCOSX approximation, which involves different approximations for the formation of the Coulomb- and exchange-type matrices, to MP2 theory is demonstrated and is benchmarked against the original MP2 and the already highly efficient RI-MP2 method.Abstract:
Efficient energy calculations and structure optimizations employing second-order Moller−Plesset perturbation theory (MP2) are presented. The application of the RIJCOSX approximation, which involves different approximations for the formation of the Coulomb- and exchange-type matrices, to MP2 theory is demonstrated. The RIJCOSX approximation incorporates the ‘resolution of the identity’ approximation in terms of a Split-RI-J variant for the evaluation of the Coulomb matrices and a seminumeric exchange treatment via the ‘chain-of-spheres’ algorithm for the formation of the exchange-type matrices. Beside the derivation of the working equations, the RIJCOSX-MP2 method is benchmarked against the original MP2 and the already highly efficient RI-MP2 method. Energies as well as gradients are computed employing various basis sets and are compared to the conventional MP2 results concerning accuracy and total wall clock times. Speedups of typically a factor of 5−7 in comparison to MP2 can be obeserved for the largest...read more
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An overlap fitted chain of spheres exchange method.
Róbert Izsák,Frank Neese +1 more
TL;DR: The main idea is finding a fitting matrix, Q, which leads the numerical and analytically evaluated overlap matrices to coincide, which results in a reduction of grid sizes necessary for achieving chemical accuracy and improves the efficiency of the COS method.
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Benchmark structures and binding energies of small water clusters with anharmonicity corrections.
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References
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Journal ArticleDOI
Note on an Approximation Treatment for Many-Electron Systems
Chr. Møller,Milton S. Plesset +1 more
TL;DR: In this article, a perturbation theory for treating a system of n electrons in which the Hartree-Fock solution appears as the zero-order approximation was developed, and it was shown by this development that the first order correction for the energy and the charge density of the system is zero.
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Fully optimized contracted Gaussian basis sets for atoms Li to Kr
TL;DR: In this article, various contracted Gaussian basis sets for atoms up to Kr are presented which have been determined by optimizing atomic self-consistent field ground state energies with respect to all basis set parameters, i.e., orbital exponents and contraction coefficients.
Journal ArticleDOI
Fully optimized contracted Gaussian basis sets of triple zeta valence quality for atoms Li to Kr
TL;DR: In this article, a triple zeta valence (TZV) basis set is presented for Li to Kr. The TZV bases are characterized by typically including a single contraction to describe inner shells and three basis functions for valence shells.
Journal ArticleDOI
Accurate Coulomb-fitting basis sets for H to Rn
TL;DR: A series of auxiliary basis sets to fit Coulomb potentials for the elements H to Rn (except lanthanides) is presented and computation times for the Coulomb part are reduced by a factor of ca.15 kJ mol(-1) per atom.
Journal ArticleDOI
Auxiliary basis sets for main row atoms and transition metals and their use to approximate Coulomb potentials
TL;DR: In this paper, the auxilliary basis sets for the atoms H to At were optimized for an efficient treatment of molecular electronic Coulomb interactions for molecules with up to 300 atoms and 2500 basis functions.