Understanding biomolecules, their structures and interactions
with solvent such as water, is essential to revealing mechanisms
and functions of biological systems. While atomistic simulations
that treat both solvent and solute molecules explicitly are
usually more accurate, implicit or continuum solvent models for
biomolecules are far more efficient. In this talk, I will first
introduce a new class of accurate implicit solvent models, termed variational implicit solvent models, for biomolecules. Central in this model is a free energy functional of all admissible
solute-solvent interfaces, coupling both nonpolar and polar
contributions of an underlying system. An energy-minimizing
interface then defines a molecular surface in solution. I will
then describe a level-set method for the numerical calculation of equilibrium solvent-solute interface and free-energy for the
solvation of nonpolar molecules, and present extensive numerical results with comparison to molecular dynamics simulations. This is joint work with Jianwei Che, Li-Tien Cheng, Joachim Dzubiella, J. Andy McCammon, and Yang Xie.