Chen Xin, Batista Victor S
Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA.
J Chem Phys. 2006 Sep 28;125(12):124313. doi: 10.1063/1.2356477.
A simple approach for numerically exact simulations of nonadiabatic quantum dynamics in multidimensional systems is introduced and applied to the description of the photoabsorption spectroscopy of pyrazine. The propagation scheme generalizes the recently developed matching-pursuit/split-operator-Fourier-transform (MP/SOFT) method [Y. Wu and V. S. Batista, J. Chem. Phys. 121, 1676 (2004)] to simulations of nonadiabatic quantum dynamics. The time-evolution operator is applied, as defined by the Trotter expansion to second order accuracy, in dynamically adaptive coherent-state expansions. These representations are obtained by combining the matching-pursuit algorithm with a gradient-based optimization method. The accuracy and efficiency of the resulting computational approach are demonstrated in calculations of time-dependent survival amplitudes and photoabsorption cross sections, using a model Hamiltonian that allows for direct comparisons with benchmark calculations. Simulations in full-dimensional potential energy surfaces involve the propagation of a 24-dimensional wave packet to describe the S(1)S(2) interconversion of pyrazine after S(0)-->S(2) photoexcitation. The reported results show that the generalized MP/SOFT method is a practical and accurate approach to model nonadiabatic reaction dynamics in polyatomic systems.
介绍了一种用于多维系统中非绝热量子动力学数值精确模拟的简单方法，并将其应用于吡嗪光吸收光谱的描述。该传播方案将最近开发的匹配追踪/分裂算符傅里叶变换（MP/SOFT）方法[Y. Wu和V. S. Batista，《化学物理杂志》121, 1676 (2004)]推广到非绝热量子动力学模拟。时间演化算符按照Trotter展开定义到二阶精度，应用于动态自适应相干态展开。这些表示通过将匹配追踪算法与基于梯度的优化方法相结合获得。使用一个允许与基准计算直接比较的模型哈密顿量，在计算时间相关的存活振幅和光吸收截面时，证明了所得计算方法的准确性和效率。在全维势能面上的模拟涉及一个24维波包的传播，以描述吡嗪在S(0)→S(2)光激发后的S(1)S(2)相互转换。报告的结果表明，广义MP/SOFT方法是一种实用且准确的方法，可用于模拟多原子系统中的非绝热反应动力学。
