An efficient method for computing excess free energy of liquid  

作　　者：Jianing Song Linqiong Qiu John Z.H. Zhang 

机构地区：[1]School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China [2]NYU-ECNU Center for Computational Chemistry at NYU ShanghaL Shanghai 200062, China [3]State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China [4]Department of Chemistry, New York University, NY, NY 10003, USA

出　　处：《Science China Chemistry》2018年第1期135-140,共6页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China (21603144, 21433004);Ministry of Science and Technology of China (2016YFA0501700);NYU Global Seed Grant, Shanghai Putuo District (2014-A-02);Shanghai Sailing Program (2016YF1408400)

摘　　要：We present a new theoretical method for efficient calculation of free energy of liquid. This interaction entropy method allows one to compute entropy and free energy of liquid from standard single step MD(molecular dynamics) simulation directly in liquid state without the need to perform MD simulations at many intermediate states as required in thermodynamic integration or free energy perturbation methods. In this new approach, one only needs to evaluate the interaction energy of a single(fixed) liquid molecule with the rest of liquid molecules as a function of time from a standard MD simulation of liquid and the fluctuation of distribution of this interaction energy is then used to calculate the interaction entropy of the liquid. Explicit theoretical derivation of this interaction entropy approach is provided and numerical calculations for the benchmark liquid water system were carried out using three different water models. Numerical analysis of the result was performed and comparison of the computational result with experimental data and other theoretical results were provided. Excellent agreement of calculated free energies with the experimental data using TIP4 P model is obtained for liquid water.We present a new theoretical method for efficient calculation of free energy of liquid. This interaction entropy method allows one to compute entropy and free energy of liquid from standard single step MD （molecular dynamics） simulation directly in liquid state without the need to perform MD simulations at many intermediate states as required in thermodynamic integration or free energy perturbation methods. In this new approach, one only needs to evaluate the interaction energy of a single （fixed） liquid molecule with the rest of liquid molecules as a function of time from a standard MD simulation of liquid and the fluctuation of distribution of this interaction energy is then used to calculate the interaction entropy of the liquid. Explicit theoretical derivation of this interaction entropy approach is provided and numerical calculations for the benchmark liquid water system were carried out using three different water models. Numerical analysis of the result was performed and comparison of the computational result with experimental data and other theoretical results were provided. Excellent agreement of calculated free energies with the experimental data using TIP4P model is obtained for liquid water.

关 键 词：excess free energy LIQUID MD simulation interaction entropy 

分 类 号：N0[自然科学总论—科学技术哲学]