Park Jae Woo, Rhee Young Min
Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang 790-784, KoreaDepartment of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea.
J Chem Phys. 2014 Apr 28;140(16):164112. doi: 10.1063/1.4872155.
Simulating molecular dynamics directly on quantum chemically obtained potential energy surfaces is generally time consuming. The cost becomes overwhelming especially when excited state dynamics is aimed with multiple electronic states. The interpolated potential has been suggested as a remedy for the cost issue in various simulation settings ranging from fast gas phase reactions of small molecules to relatively slow condensed phase dynamics with complex surrounding. Here, we present a scheme for interpolating multiple electronic surfaces of a relatively large molecule, with an intention of applying it to studying nonadiabatic behaviors. The scheme starts with adiabatic potential information and its diabatic transformation, both of which can be readily obtained, in principle, with quantum chemical calculations. The adiabatic energies and their derivatives on each interpolation center are combined with the derivative coupling vectors to generate the corresponding diabatic Hamiltonian and its derivatives, and they are subsequently adopted in producing a globally defined diabatic Hamiltonian function. As a demonstration, we employ the scheme to build an interpolated Hamiltonian of a relatively large chromophore, para-hydroxybenzylidene imidazolinone, in reference to its all-atom analytical surface model. We show that the interpolation is indeed reliable enough to reproduce important features of the reference surface model, such as its adiabatic energies and derivative couplings. In addition, nonadiabatic surface hopping simulations with interpolation yield population transfer dynamics that is well in accord with the result generated with the reference analytic surface. With these, we conclude by suggesting that the interpolation of diabatic Hamiltonians will be applicable for studying nonadiabatic behaviors of sizeable molecules.
直接在量子化学获得的势能面上模拟分子动力学通常很耗时。尤其是当目标是激发态动力学以及多个电子态时，成本会变得过高。在从小分子的快速气相反应到具有复杂环境的相对缓慢的凝聚相动力学等各种模拟场景中，插值势已被提议作为解决成本问题的一种方法。在此，我们提出一种用于插值相对较大分子的多个电子表面的方案，旨在将其应用于研究非绝热行为。该方案从绝热势信息及其 diabatic 变换开始，原则上这两者都可以通过量子化学计算轻松获得。每个插值中心的绝热能量及其导数与导数耦合矢量相结合，以生成相应的 diabatic 哈密顿量及其导数，随后将它们用于生成全局定义的 diabatic 哈密顿量函数。作为一个示例，我们采用该方案构建了一个相对较大的发色团对羟基苄叉咪唑啉酮的插值哈密顿量，参考其全原子解析表面模型。我们表明，插值确实足够可靠，能够重现参考表面模型的重要特征，例如其绝热能量和导数耦合。此外，使用插值的非绝热表面跳跃模拟产生的布居转移动力学与参考解析表面产生的结果非常一致。基于这些，我们得出结论，diabatic 哈密顿量的插值将适用于研究相当大的分子的非绝热行为。
