Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions
Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions
复制标题
DOI：
10.1063/1.3190169
复制
发表时间：
2009-08-14
影响因子：
4.4
通讯作者：
Blumberger, Jochen
中科院分区：
文献类型：
--
作者：
Oberhofer, Harald;Blumberger, Jochen
提出了一种基于平面波基组的电荷约束密度泛函分子动力学（CDFT-MD）方法，用于模拟凝聚相体系中的电子转移反应。根据Wu和货车Voorhis的早期工作[Phys.Rev.A72，024502（2005）]，在供体和受体之间的电荷差等于给定值的约束下使密度泛函最小化。经典离子动力学在电荷约束态的Born-Oppenheimer面上传播。我们调查的约束能量和能隙的定义上的电荷和约束力的表达式的依赖。将该方法应用于水溶液中Ru ~（2+）-Ru ~（3+）的电子自交换反应。采样的垂直能隙沿着CDFT-MD轨迹和有限尺寸效应校正，重组自由能为1.6 eV。这是0.1-0.2电子伏特低于先前的估计的基础上连续模型的溶剂化。重组自由能的较小值可以解释的事实，即二价和三价Ru六水合物的Ru-O距离的预测是更相似的电子转移络合物比分离的水离子。
We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following the earlier work of Wu and Van Voorhis [Phys. Rev. A 72, 024502 (2005)], the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge and present expressions for the constraint forces. The method is applied to the Ru2+-Ru3+ electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. The smaller value for the reorganization free energy can be explained by the fact that the Ru-O distances of the divalent and trivalent Ru hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua ions.