A novel implementation of CCSD analytic gradients using Cholesky decomposition of the two-electron integrals and Abelian point-group symmetry

TL;DR

This paper introduces an efficient CCSD analytic gradient implementation that combines Cholesky decomposition of integrals with Abelian point-group symmetry, enabling faster geometry optimizations of large symmetric molecules.

Contribution

The paper presents a novel method integrating Cholesky decomposition with symmetry exploitation for CCSD gradients, improving computational efficiency for large systems.

Findings

Significant reduction in computational time for medium-sized molecules.

Successful geometry optimizations with hundreds of basis functions.

Quantified efficiency gains from symmetry exploitation.

Abstract

We present a novel and efficient implementation of coupled-cluster with singles and doubles (CCSD) analytic gradients that combines the Cholesky decomposition (CD) of electron-repulsion integrals with the exploitation of Abelian point-group symmetry. This approach is particularly effective for medium-sized and large symmetric molecular systems. The CD of two-electron integrals is performed using a symmetry-adapted two-step algorithm, while the derivatives of the Cholesky vectors are computed with respect to symmetry-adapted nuclear displacements and contracted on-the-fly with the CCSD density matrices. Geometry optimizations of symmetric systems with several hundreds of basis functions have been carried out to assess the efficiency of our implementation and to quantify the computational gain provided by the exploitation of point-group symmetry.