Coupled Cluster Calculations: Ovos as an Alternative Avenue Towards Treating Still Larger Molecules

Abstract

An overview of basic principles and different concepts of the Optimized Virtual Orbital Space (OVOS) method and its applications is presented. The objective is to show that the OVOS is a tool that allows extending the applicability of Coupled Cluster calculations to larger systems with larger basis sets it was possible before. We describe some instruments which serve as a measure of the accuracy of the CC calculation upon the OVOS truncation supplemented with a short outline of how to get a balanced reduction of virtual orbital space for all species participating in, e.g., calculation of reaction or interaction energies. We demonstrate the performance of the OVOS technique in different areas, including molecular electric properties, electron affinities, intermolecular interactions and some other applications. We also present some examples of large scale CCSD(T) calculations, which illustrate the computational efficiency of the OVOS approach.