Scalable Ab Initio Electronic Structure Methods with Near Chemical Accuracy for Main Group Chemistry

TL;DR

This paper assesses the accuracy of scalable quantum chemical methods, DLPNO-CCSD(T) and localized ph-AFQMC, demonstrating they achieve near chemical accuracy for main group thermochemistry, enabling broader scientific applications.

Contribution

It provides a comprehensive evaluation of scalable methods achieving chemical accuracy, expanding their validated use in chemistry and materials science.

Findings

Both methods achieve RMSD < 1 kcal/mol across datasets.

Maximum deviations are confined within 2 kcal/mol.

Methods are suitable for complex biological and materials applications.

Abstract

This study evaluates the precision of widely recognized quantum chemical methodologies, CCSD(T), DLPNO-CCSD(T) and localized ph-AFQMC, for determining the thermochemistry of main group elements. DLPNO-CCSD(T) and localized ph-AFQMC, which offer greater scalability compared to canonical CCSD(T), have emerged over the last decade as pivotal in producing precise benchmark chemical data. Our investigation includes closed-shell, neutral molecules, focusing on their heat of formation and atomization energy sourced from four specific small molecule datasets. Firstly, we selected molecules from the G2 and G3 datasets, noted for their reliable experimental heat of formation data. Additionally, we incorporate molecules from the W4-11 and W4-17 sets, which provide high-level theoretical reference values for atomization energy at 0 K. Our findings reveal that both DLPNO-CCSD(T) and ph-AFQMC methods are capable of achieving a root-mean-square deviation (RMSD) of less than 1 kcal/mol across the combined dataset, aligning with the threshold for chemical accuracy. Moreover, we make efforts to confine the maximum deviations within 2 kcal/mol, a degree of precision that significantly broadens the applicability of these methods in fields such as biology and materials science.