Quantum Mechanical Methods for Biomolecular Simulations.

We discuss quantum mechanical methods for the description of the potential energy surface and for the treatment of nuclear quantum effects in chemical and biological applications. Two novel electronic structure methods are described, including an electronic structure-based explicit polarization (X-Pol) force field and an effective Hamiltonian molecular orbital and valence bond (EH-MOVB) theory. In addition, we present two path integral techniques to treat nuclear quantum effects, which include an analytical pathintegral method based on Kleinert's variational perturbation theory, and integrated pathintegral free-energy perturbation and umbrella sampling (PI-FEP/UM) simulation. Studies have shown that quantum mechanics can be applied to biocatalytic systems in a variety of ways and scales. We hope that the methods presented in this article can further expand the scope of quantum mechanical applications to biomolecular systems