Integral Equation Theory of Molecular Solvation Coupled with Quantum Mechanical/Molecular Mechanics Method in NWChem Package

We have developed a hybrid approach based on a combination of integral equation theory of molecular liquids and quantum mechanical/molecular mechanics (QM/MM) methodology in North West computational Chemistry (NWChem) software package. We have split the evaluations into consequent QM/MM and statistical mechanics calculations based on the one-dimensional reference interaction site model, which allows us to reduce significantly the time of computation. The method complements QM/MM capabilities existing in the NWChem package. The accuracy of the presented method was tested through computation of the water structure around several organic solutes and their hydration free energies. We have also evaluated the solvent effect on the conformational equilibria. The applicability and limitations of the developed approach are discussed.