title: A Site Density Functional Theory for Water: Application to Solvation of Amino Acid Side Chains.
abstract: We report a site density functional theory (SDFT) based on the conventional atomistic models of water and the universality ansatz of the bridge functional. The excess Helmholtz energy functional is formulated in terms of a quadratic expansion with respect to the local density deviation from that of a uniform system and a universal functional for all higher-order terms approximated by that of a reference hard-sphere system. With the atomistic pair direct correlation functions of the uniform system calculated from MD simulation and an analytical expression for the bridge functional from the modified fundamental measure theory, the SDFT can be used to predict the structure and thermodynamic properties of water under inhomogeneous conditions with a computational cost negligible in comparison to that of brute-force simulations. The numerical performance of the SDFT has been demonstrated with the predictions of the solvation free energies of 15 molecular analogs of amino acid side chains in water represented by SPC/E, SPC, and TIP3P models. For theTIP3P model, a comparison of the theoretical predictions with MD simulation and experimental data shows agreement within 0.64 and 1.09 kcal/mol on average, respectively.
authors.affiliation: Departments of Chemical and Environmental Engineering and Mathematics, University of California, Riverside, California 92521, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, 200238, P. R. China.
authors.forename: Shuangliang
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Departments of Chemical and Environmental Engineering and Mathematics, University of California, Riverside, California 92521, United States.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Wu