Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
J Chem Phys. 2019 Sep 14;151(10):104311. doi: 10.1063/1.5111547.
We have employed extended multiconfiguration quasidegenerate perturbation theory, fourfold-way diabatic molecular orbitals, and configurational uniformity to develop a global three-state diabatic representation of the potential energy surfaces and their couplings for the electronically nonadiabatic reaction OH + H → HO + H, where denotes electronic excitation to the A Σ state. To achieve sign consistency of the computed diabatic couplings, we developed a graphics processing unit-accelerated algorithm called the cluster-growing algorithm. Having obtained consistent signs of the diabatic couplings, we fit the diabatic matrix elements (which consist of the diabatic potentials and the diabatic couplings) to analytic representations. Adiabatic potential energy surfaces are generated by diagonalizing the 3 × 3 diabatic potential energy matrix. The comparisons between the fitted and computed diabatic matrix elements and between the originally computed adiabatic potential energy surfaces and those generated from the fits indicate that the current fit is accurate enough for dynamical studies, and it may be used for quantal or semiclassical dynamics calculations.
我们采用扩展多组态微扰理论、四叉绝热分子轨道和构型均匀性，开发了一个用于电子非绝热反应 OH + H → HO + H 的全局三态非绝热势能面及其耦合的表示方法，其中 表示电子激发到 A Σ 态。为了实现计算得到的非绝热耦合的符号一致性，我们开发了一种称为聚类增长算法的图形处理单元加速算法。获得一致的非绝热耦合符号后，我们将非绝热矩阵元（由非绝热势能和非绝热耦合组成）拟合到解析表示中。通过对角化 3×3 非绝热势能矩阵来生成绝热势能面。拟合和计算得到的非绝热矩阵元和最初计算得到的绝热势能面与从拟合中生成的那些之间的比较表明，当前的拟合对于动力学研究足够准确，并且可以用于量子或半经典动力学计算。
