Fast evaluation of a linear number of local exchange matrices

A fast method is described for evaluating multiple exchange matrices in a Gaussian atomic orbital basis. For insulators, it is asymptotically linear scaling, and is a generalization of the linear scaling exchange (LinK) method, which was formulated for a single exchange matrix [J. Chem. Phys. 109 (1998) 1663]. It is employed to evaluate exchange-type contractions of all derivative density matrices with two-electron integrals for a series of linear alkanes, linear polyacenes, and water clusters using STO-3G, 3-21G, and 6-31G* basis sets. Significant computational savings are obtained for molecules with as few as 10 non-hydrogen atoms.

Introduction to proceedings of Molecular Quantum Mechanics 2013: electron correlation: the many-body problem at the heart of chemistry

Q-Chem 2.0: a high-performanceab initio electronic structure program package

ABSTRACT: Q-Chem 2.0 is a new release of an electronic structure programpackage, capable of performing first principles calculations on the ground andexcited states of molecules using both density functional theory and wavefunction-based methods. A review of the technical features contained withinQ-Chem 2.0 is presented. This article contains brief descriptive discussions of thekey physical features of all new algorithms and theoretical models, together withsample calculations that illustrate their performance. c 2000 John Wiley S electronic structure; density functional theory;computer program; computational chemistry Introduction A reader glancing casually at this article mightsuspect on t…

The Ground State Electronic Energy of Benzene.

We report on the findings of a blind challenge devoted to determining the frozen-core, full configuration interaction (FCI) ground state energy of the benzene molecule in a standard correlation-consistent basis set of double-$\zeta$ quality. As a broad international endeavour, our suite of wave function-based correlation methods collectively represents a diverse view of the high-accuracy repertoire offered by modern electronic structure theory. In our assessment, the evaluated high-level methods are all found to qualitatively agree on a final correlation energy, with most methods yielding an estimate of the FCI value around $-863$ m$E_{\text{H}}$. However, we find the root-mean-square devia…