Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy.
J Chem Phys. 2010 Jul 7;133(1):014106. doi: 10.1063/1.3454683.
Continuum solvation models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable continuum model (PCM) is one of the most versatile among the continuum models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the continuum polarization (represented by the apparent surface charges), the solute's atomic coordinates and-possibly-its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute's geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.
连续溶剂模型被广泛用于准确估计溶剂对复杂分子体系能量、结构和光谱性质的影响。在连续模型中，极化连续模型（PCM）是最通用的模型之一，因为它可以计算多种性质，并且可以使用多种方法来描述溶质，从分子力学（MM）到复杂的量子力学（QM）后自洽场方法，甚至混合 QM/MM 方法。在本贡献中，我们提出了一种新的 PCM 表述，它是自由能泛函的一种形式，其变分参数包括连续极化（由表观表面电荷表示）、溶质的原子坐标和-可能-它的电子密度。寻找（极化）溶质的优化几何形状及其相应的自洽反应场的问题被重新表述为最小化这个自由能泛函，同时涉及所有变量。讨论了这种 PCM 变分表述的许多潜在应用，包括同时优化溶质的几何形状和极化电荷以及扩展拉格朗日动力学。特别是，我们详细描述了同时优化过程，并包含了几个数值示例。
