摘要翻译：
多态经验价键(EVB)模型可以准确地描述复杂分子体系中质子转移和溶剂化的能量学，可以有效地用于分子动力学计算机模拟。在这些模型中，运动质子电荷的位置可以由所谓的电荷中心来指定，电荷中心定义为EVB模型非绝热态的加权平均值。本文用一阶微扰理论计算了在电荷中心施加偏置势时所产生的分子力。当分子动力学模拟用于确定与质子转移相关的自由能时，这种偏压势往往是必要的，而在可用的计算时间内，并不是所有相关的质子位置都以足够的频率采样。我们导出的力表达式易于评估，与无偏EVB模拟相比，不会产生任何显著的计算代价。作为该方法的一个例子，我们研究了由128个水分子和一个多余的质子组成的小液态水滴中的质子转移。与连续静电学的预测相反，但与以前类似系统的计算机模拟一致，我们观察到多余的质子主要位于液滴的表面。利用本文提出的形式，我们计算了将质子电荷从液滴表面带到其核心所需的可逆功，得到了大约4$K_{\rm B}t$的值。
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英文标题：
《Biasing the center of charge in molecular dynamics simulations with
  empirical valence bond models: free energetics of an excess proton in a water
  droplet》
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作者：
J\"urgen K\"ofinger, Christoph Dellago
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Soft Condensed Matter        软凝聚态物质
分类描述：Membranes, polymers, liquid crystals, glasses, colloids, granular matter
膜，聚合物，液晶，玻璃，胶体，颗粒物质
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一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  Multistate empirical valence bond (EVB) models provide an accurate description of the energetics of proton transfer and solvation in complex molecular systems and can be efficiently used in molecular dynamics computer simulations. Within such models, the location of the moving protonic charge can be specified by the so called center of charge, defined as a weighted average over the diabatic states of the EVB model. In this paper, we use first order perturbation theory to calculate the molecular forces that arise if a bias potential is applied to the center of charge. Such bias potentials are often necessary when molecular dynamics simulations are used to determine free energies related to proton transfer and not all relevant proton positions are sampled with sufficient frequency during the available computing time. The force expressions we derive are easy to evaluate and do not create any significant computational cost compared with unbiased EVB-simulations. As an illustration of the method, we study proton transfer in a small liquid water droplet consisting of 128 water molecules plus an excess proton. Contrary to predictions of continuum electrostatics but in agreement with previous computer simulations of similar systems, we observe that the excess proton is predominantly located at the surface of the droplet. Using the formalism developed in this paper, we calculate the reversible work required to carry the protonic charge from the droplet surface to its core finding a value of roughly 4 $k_{\rm B}T$.
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PDF链接：
https://arxiv.org/pdf/711.0577