Coupled cluster theory on modern heterogeneous supercomputers

Abstract

This study examines the computational challenges in elucidating intricate chemical systems, particularly through ab-initio methodologies. This work highlights the Divide-Expand-Consolidate (DEC) approach for coupled cluster (CC) theory—a linear-scaling, massively parallel framework—as a viable solution. Detailed scrutiny of the DEC framework reveals its extensive applicability for large chemical systems, yet it also acknowledges inherent limitations. To mitigate these constraints, the cluster perturbation theory is presented as an effective remedy. Attention is then directed towards the CPS (D-3) model, explicitly derived from a CC singles parent and a doubles auxiliary excitation space, for computing excitation energies. The reviewed new algorithms for the CPS (D-3) method efficiently capitalize on multiple nodes and graphical processing units, expediting heavy tensor contractions. As a result, CPS (D-3) emerges as a scalable, rapid, and precise solution for computing molecular properties in large molecular systems, marking it an efficient contender to conventional CC models.

Analytical Gradient Using Cluster-in-Molecule RI-MP2 Method for the Geometry Optimizations of Large Systems

“…These methods can be classified into two categories. The first, often referred to as direct local correlation methods, treats the entire molecule at once by omitting insignificant contributions. − The second category is the cluster-based methods, obtaining the total correlation energy as the sum of contributions from smaller clusters containing a subset of occupied LMOs and their virtual orbitals. − Although both direct and cluster-based methods can achieve a linear scaling computational cost with the system size, the cluster-based methods require much less storage and thus are applicable to much larger systems. Resolution-of-the-identity (RI) − approximation, a technique employed to accelerate electronic structure calculations by approximating the four-index two-electron integrals with two- and three-index integrals, can be combined with local correlation methods to further reduce the computational costs.…”