Effect of the Solute Cavity on the Solvation Energy and its Derivatives within the Framework of the Gaussian Charge Scheme
Effect of the Solute Cavity on the Solvation Energy and its Derivatives within the Framework of the Gaussian Charge Scheme
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DOI：
10.1002/jcc.26139
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发表时间：
2019-12-30
影响因子：
3
通讯作者：
Neese, Frank
中科院分区：
文献类型：
--
作者：
Garcia-Rates, Miquel;Neese, Frank
在可极化连续介质模型中用高斯函数处理溶剂化电荷，得到了一个光滑的势能面。这些电荷被放置在溶质腔表面的顶部。在这篇文章中，我们研究的溶质腔（货车范德华型或溶剂排斥表面型）的影响，使用高斯电荷方案的框架内的导体极化连续模型（a）的准确性和计算成本的自洽场（SCF）的能量和它的梯度和（B）的计算的自由能的溶剂化。为此目的，我们已经考虑了大量的系统，从几个原子到200多个原子在不同的溶剂中。我们在DFT水平上使用B3 LYP泛函和def 2-TZVP基组的结果表明，溶质腔的选择既不影响小系统（< 100个原子）的计算精度，也不影响计算成本。对于较大的系统，建议使用vdw型腔，因为它可以防止梯度中的小振荡（使用SES型腔时存在），这会影响SCF能量梯度的收敛。关于溶剂化的自由能，我们考虑了溶剂依赖的探针球来构建溶剂可及的表面积，以计算溶剂化的自由能的非静电贡献。对于这一部分，我们的结果为一个大的有机分子在不同的溶剂中同意与现有的实验数据的精度低于1千卡/摩尔的极性和非极性溶剂。
The treatment of the solvation charges using Gaussian functions in the polarizable continuum model results in a smooth potential energy surface. These charges are placed on top of the surface of the solute cavity. In this article, we study the effect of the solute cavity (van der Waals-type or solvent-excluded surface-type) using the Gaussian charge scheme within the framework of the conductor-like polarizable continuum model on (a) the accuracy and computational cost of the self-consistent field (SCF) energy and its gradient and on (b) the calculation of free energies of solvation. For that purpose, we have considered a large set of systems ranging from few atoms to more than 200 atoms in different solvents. Our results at the DFT level using the B3LYP functional and the def2-TZVP basis set show that the choice of the solute cavity does neither affect the accuracy nor the cost of calculations for small systems (< 100 atoms). For larger systems, the use of a vdW-type cavity is recommended, as it prevents small oscillations in the gradient (present when using a SES-type cavity), which affect the convergence of the SCF energy gradient. Regarding the free energies of solvation, we consider a solvent-dependent probe sphere to construct the solvent-accessible surface area required to calculate the nonelectrostatic contribution to the free energy of solvation. For this part, our results for a large set of organic molecules in different solvents agree with available experimental data with an accuracy lower than 1 kcal/mol for both polar and nonpolar solvents.