The Cluster-in-Molecule Local Correlation Method with an Accurate Distant Pair Correction for Large Systems

TL;DR

This paper introduces an enhanced cluster-in-molecule local correlation method with a new distant pair correction, enabling highly accurate energy predictions for large molecular systems with minimal additional computational effort.

Contribution

It presents a simple, efficient scheme for distant pair correlation correction within the CIM approach, significantly improving accuracy for large systems.

Findings

Recovered over 99.97% of conventional correlation energy

Achieved accurate binding energies for large weakly bound complexes

Assessed various correlation and density functional methods for large systems

Abstract

The cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction is presented. For large systems, the inclusion of distant pair correlation energies is essential for the accurate predictions of absolute correlation energies and relative energies. Here we propose a simple and efficient scheme for evaluating the distant pair correlation energy correction. The corrections can be readily extracted from electron correlation calculations of clusters with almost no additional effort. Benchmark calculations show that the improved CIM approach can recover more than 99.97% of the conventional correlation energy. By combining the CIM approach with the domain based local pair natural orbital (DLPNO) local correlation approach, we have provided accurate binding energies at the CIM-DLPNO-CCSD(T) level for a test set consisting of eight weakly bound complexes ranging in size from 200 to 1027 atoms. With these results as the reference data, the accuracy and applicability of other electron correlation methods and a few density functional methods for large systems have been assessed.