Enabling rapid and accurate construction of CCSD(T)-level potential energy surface of large molecules using molecular tailoring approach

TL;DR

This paper demonstrates that the molecular tailoring approach (MTA) enables efficient and accurate construction of CCSD(T)-level potential energy surfaces for large molecules, significantly reducing computational time while maintaining high accuracy.

Contribution

It introduces the application of MTA for CCSD(T) calculations on large molecules, achieving high accuracy with reduced computational cost.

Findings

MTA energies agree with full calculations within sub-millihartree error

Time savings of 3 to 5 times compared to full calculations

Accurate estimation of energy barriers and gradients

Abstract

The construction of the potential energy surface (PES) of even a medium-sized molecule employing correlated theory, such as CCSD(T), is an arduous task due to the high computational cost. In this Letter, we report the possibility of efficient construction of such a PES employing the molecular tailoring approach (MTA) on off-the-shelf hardware. The full calculation (FC) as well as MTA energies at CCSD(T)/aug-cc-pVTZ level for three test molecules, viz. acetylacetone, N-methyacetamide, and tropolone are reported. All the MTA energies are in excellent agreement with their FC counterparts (typical error being sub-millihartree) with a time advantage factor of 3 to 5. The energy barrier from the ground- to transition-state is accurately captured. Further, the accuracy and efficiency of the MTA method for estimating energy gradients at CCSD(T) level are demonstrated. This work brings out the possibility of the construction of PES for large molecules using MTA with the computational economy at a high level of theory and/or basis set.