Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
J Phys Condens Matter. 2010 Jul 21;22(28):284116. doi: 10.1088/0953-8984/22/28/284116. Epub 2010 Jun 21.
In this contribution we review our recently developed method for the calculation of acidity constants from density functional theory based molecular dynamics simulations. The method is based on a half reaction scheme in which protons are formally transferred from solution to the gas phase. The corresponding deprotonation free energies are computed from the vertical energy gaps for insertion or removal of protons. Combined to full proton transfer reactions, the deprotonation energies can be used to estimate relative acidity constants and also the Brønsted pK(a) when the deprotonation free energy of a hydronium ion is used as a reference. We verified the method by investigating a series of organic and inorganic acids and bases spanning a wide range of pK(a) values (20 units). The thermochemical corrections for the biasing potentials assisting and directing the insertion are discussed in some detail.
在本研究中，我们回顾了最近开发的一种基于密度泛函理论的分子动力学模拟来计算酸度常数的方法。该方法基于一个半反应方案，其中质子从溶液中正式转移到气相中。相应的去质子化自由能是通过插入或去除质子的垂直能量间隙计算得到的。与完整的质子转移反应相结合，去质子化能量可用于估计相对酸度常数，也可用于当以水合氢离子的去质子化自由能作为参考时估计布伦斯特 pK(a)。我们通过研究一系列具有广泛 pK(a)值（20 个单位）的有机和无机酸碱来验证该方法。详细讨论了辅助和指导插入的偏置势的热化学校正。
