Convergence of the many-body expansion with respect to distance cutoffs in crystals of polar molecules: Acetic acid, formamide, and imidazole

Philip M Nelson; C David Sherrill

doi:10.1063/5.0234883

Convergence of the many-body expansion with respect to distance cutoffs in crystals of polar molecules: Acetic acid, formamide, and imidazole

J Chem Phys. 2024 Dec 7;161(21):214105. doi: 10.1063/5.0234883.

Authors

Philip M Nelson¹, C David Sherrill¹

Affiliation

¹ Center for Computational Molecular Science and Technology, School of Chemistry and Biochemistry, and School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

PMID: 39625315
DOI: 10.1063/5.0234883

Abstract

The many-body expansion, where one computes the total energy of a supersystem as the sum of the dimer, trimer, tetramer, etc., subsystems, provides a convenient approach to compute the lattice energies of molecular crystals. We investigate approximate methods for computing the non-additive three-body contributions to the crystal lattice energy of the polar molecules acetic acid, imidazole, and formamide, comparing to coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] level benchmarks. Second-order Møller-Plesset perturbation theory (MP2), if combined with a properly damped Axilrod-Teller-Muto dispersion potential, displays excellent agreement with CCSD(T) at a substantially reduced cost. Errors between dispersion-corrected MP2 and CCSD(T) are less than 1 kJ mol-1 for all three crystals. However, the three-body energy requires quite large distance cutoffs to converge, up to 20 Å or more.