Benchmark interaction energies for biologically relevant noncovalent complexes containing divalent sulfur

Abstract

Molecules containing divalent sulfur can participate in significant hydrogen bonding interactions. Computing accurate noncovalent interaction energies requires a proper description of electron correlation effects. Coupled-cluster theory with single and double substitutions and perturbutative triple substitutions, CCSD(T), using extrapolation to the complete basis set (CBS) limit has become the method of choice for computing accurate interaction energies of noncovalently bound complexes. Following the procedure used to develop the S66 benchmark set of noncovalent interaction energies relevant to biomolecular structures [J. Chem. Theory Comput. (2011)], interaction energies are computed for ten hydrogen-bonded complexes of biological relevance that contain divalent sulfur. Equilibrium geometries and eight-point estimated CCSD(T)/CBS potential energy curves along the noncovalent interaction vector are computed for each complex. As a comparison of high-accuracy ab initio methods, interaction energies are also calculated using the correlation-consistent Composite Approach (ccCA). We find that the two methods yield energies within a few hundredths of a kcal mol^-1 of each other in nearly all cases. The interaction energies provided here should be useful for developing and assessing the accuracy of more approximate ab initio, density functional theory, semi-empirical and classical force field approaches.