FINITE REPRESENTATION OF AN INFINITE BULK SYSTEM - SOLVENT BOUNDARY POTENTIAL FOR COMPUTER-SIMULATIONS
FINITE REPRESENTATION OF AN INFINITE BULK SYSTEM - SOLVENT BOUNDARY POTENTIAL FOR COMPUTER-SIMULATIONS
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DOI：
10.1063/1.466711
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发表时间：
1994-06-15
影响因子：
4.4
通讯作者：
ROUX, B
中科院分区：
文献类型：
--
作者：
BEGLOV, D;ROUX, B
本文提出了一种从有限团簇的计算机模拟中获得类似于无限体系统的统计性质的方法。一个严格的理论公式给出的溶剂边界电位，考虑到周围的散装的影响。溶剂边界势是由任意溶质和嵌入在可变半径的硬球内的有限数量的显式溶剂分子组成的有效簇的构型依赖的溶剂化自由能;硬球不直接作用于溶质或显式溶剂分子，并且其半径根据瞬时构型而变化。该配方如下从一个精确的分离的多维构型玻尔兹曼积分的溶剂分子最接近的溶质和剩余的散装溶剂分子。在恒定压力下，包括货车德瓦尔斯和静电相互作用的影响，溶剂边界势的近似构造的模拟散装水。近似说明与水分子和钠和钾离子的溶剂化自由能的计算。通过对正丁烷和丙氨酸二肽在水溶液中的伞形采样计算，说明了本体溶剂对分子溶质构象平衡的影响。测试边界势以检查结果对模拟中明确包含的水分子数量的依赖性。据观察，即使当仅明确地包括第一水合壳层中的沃茨时，也获得了块状的结果。
An approach is developed to obtain statistical properties similar to those of an infinite bulk system from computer simulations of a finite cluster. A rigorous theoretical formulation is given for the solvent boundary potential which takes the influence of the surrounding bulk into account. The solvent boundary potential is the configuration-dependent solvation free energy of an effective cluster composed of an arbitrary solute and a finite number of explicit solvent molecules embedded inside a hard sphere of variable radius; the hard sphere does not act directly on the solute or the explicit solvent molecules, and its radius varies according to the instantaneous configurations. The formulation follows from an exact separation of the multidimensional configurational Boltzmann integral in terms of the solvent molecules nearest to the solute and the remaining bulk solvent molecules. An approximation to the solvent boundary potential is constructed for simulations of bulk water at constant pressure, including the influence of van der Waals and electrostatic interactions. The approximation is illustrated with calculations of the solvation free energy of a water molecule and of sodium and potassium ions. The influence of bulk solvent on the conformational equilibrium of molecular solutes is illustrated by performing umbrella sampling calculations of n-butane and alanine dipeptide in water. The boundary potential is tested to examine the dependence of the results on the number of water molecules included explicitly in the simulations. It is observed that bulk-like results are obtained, even when only the waters in the first hydration shell are included explicitly.