Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
J Chem Phys. 2011 Jul 28;135(4):044114. doi: 10.1063/1.3615493.
We describe a straightforward technique for obtaining diabatic couplings applicable to charge transfer from or charge recombination to the electronic ground state. Our method is nearly black box, requiring minimal chemical intuition from the user, and merges two well-established approaches in electronic structure theory: first, smooth and balanced adiabatic states are generated using spin-flip-configuration interaction singles (SF-CIS) based on a triplet HF state; second, Boys localization is applied to rotate all adiabatic states into charge-localized diabatic states. The method is computationally inexpensive, scaling only with the cost of CIS, and does not require a choice of active space, which is usually required for such intrinsically multiconfigurational problems. Molecular LiF in vacuum and LiF solvated by a single water molecule are examined as model systems. We find nearly smooth diabatic potential energy surfaces and couplings and we find that the Condon approximation is obeyed approximately for this model problem.
我们描述了一种简单的技术，用于获得适用于从电子基态转移电荷或复合电荷的非绝热耦合。我们的方法几乎是黑盒的，只需要用户具备最低限度的化学直觉，并且融合了电子结构理论中两种成熟的方法：首先，使用基于三重态 HF 态的自旋翻转组态相互作用单重态（SF-CIS）生成平滑且平衡的绝热态；其次，采用 Boys 局域化将所有绝热态旋转到电荷局域的非绝热态。该方法计算成本低廉，仅随 CIS 的成本而扩展，并且不需要选择通常对于这种本质上多组态问题所需的活动空间。我们以真空中的分子 LiF 和被单个水分子溶剂化的 LiF 作为模型系统进行了研究。我们发现了几乎平滑的非绝热势能表面和耦合，并且我们发现对于这个模型问题，Condon 近似近似成立。
