Calibration of the Many-Body Dispersion Range-Separation Parameter

TL;DR

This paper calibrates the range-separation parameter for many-body dispersion corrections across 24 DFT functionals, enabling more accurate modeling of noncovalent interactions with minimal error.

Contribution

It introduces a systematic calibration method and a predictive linear equation for the range-separation parameter based on functional class and gradient enhancement.

Findings

Most functionals achieve <1 kcal/mol MAE with calibrated MBD.

A linear equation predicts optimal parameters based on functional class.

Calibration improves the accuracy of DFT in modeling noncovalent interactions.

Abstract

Recent work has shown that a fully many-body treatment of noncovalent interactions, such as that given by the method of many-body dispersion (MBD), is vital to accurately modeling the structure and energetics of many molecular systems with density functional theory (DFT). To avoid double counting the correlation contributions of DFT and the MBD correction, a single-parameter range-separation scheme is typically employed. Coupling the MBD correction to a given exchange-correlation functional therefore requires calibrating the range-separation parameter. We perform this calibration for 24 popular DFT functionals by optimizing against the S66x8 benchmark set. Additionally, we report a linear equation that predicts near optimal range-separation parameters, dependent only on the class of the exchange functional and the value of the gradient enhancement factor. When a calibrated MBD correction is employed, most of the exchange-correlation functionals considered are capable of achieving agreement with CCSD(T)/CBS interaction energies in the S66x8 set to better than 1~kcal/mol mean absolute error.