Implementation of analytic gradients for CCSD and EOM-CCSD using Cholesky decomposition of the electron-repulsion integrals and their derivatives: Theory and benchmarks

Abstract

We present a general formulation of analytic nuclear gradients for the coupled-cluster with single and double substitution (CCSD) and equation-of-motion (EOM) CCSD energies computed using Cholesky decomposition (CD) representations of the electron repulsion integrals. By rewriting the correlated energy and response equations such that the storage of the largest four-index intermediates is eliminated, CD leads to a significant reduction in disk storage requirements, reduced I/O penalties, and an improved parallel performance. CD thus extends the scope of the systems that can be treated by (EOM-)CCSD methods, although analytic gradients in the framework of CD are needed to extend the applicability of (EOM-)CCSD methods in the context of geometry optimizations. This paper presents a formulation of analytic (EOM-) CCSD gradient within the CD framework and reports on the salient details of the corresponding implementation. The accuracy and the capabilities of analytic CD-based (EOM-)CCSD gradients are illustrated by benchmark calculations and several illustrative examples.Published under license by AIP Publishing. https://doi.

NWChem: Past, present, and future

“…NWChemEx is being developed to address two outstanding problems in advanced biofuels research: (i) development of a molecular understanding of proton controlled membrane transport processes and (ii) development of catalysts for the efficient conversion of biomass-derived intermediates into biofuels, hydrogen, and other bioproducts. Therefore, the main focus is on enabling scalable implementations of the groundstate canonical CC formalisms utilizing the Cholesky decomposed form of the two-electron integrals, [413][414][415][416][417][418] as well as linear scaling CC formulations based on the domain-based local pair natural orbital CC formulations (DLPNO-CC) [419][420][421] and embedding methods.…”

Coupled-cluster techniques for computational chemistry: The CFOUR program package

“…The same applies for integral derivatives. [420][421][422] We believe that this price is worth paying to retain full control on the precision of the calculation. For this reason, CD of the ERIs has been implemented in CFOUR.…”

The quest to uncover the nature of benzonitrile anion

“…Because of their structural similarity, we also expect vibrational frequencies of the neutral and DBS to be similar, giving rise to ∆ZPE≈0. ZPEs of the neutral and the VA states were computed with CCSD and EOM-EA-CCSD using aug-cc-pVDZ and resolution-of-the-identity (RI) approximation 50,51 with the matching basis set (ri-aug-cc-pVDZ), at the geometries optimized at the same level of theory. The computed structures and normal modes were used to compute the Franck-Condon factors within parallel-mode double-harmonic approximation using the ezSpectrum software 52 .…”