论文标题
残留的非绝热耦合对于准确模拟准绝热表示中的非绝热量子动力学有多重要？
How important are the residual nonadiabatic couplings for an accurate simulation of nonadiabatic quantum dynamics in a quasidiabatic representation?
论文作者
论文摘要
分子哈密顿量的糖化是一种标准方法，是在绝热势能表面的圆锥形相交处去除非绝热耦合的奇异性。通常，不可能完全消除非绝热耦合 - 由此产生的“准绝热”状态仍然与通常被忽略的较小但不存在的残留非绝热耦合相连。在这里，我们提出了一种通过比较有或没有残留耦合的量子动力学来评估这种潜在巨大近似的有效性的一般方法。为了使由于忽略残留耦合而导致错误的数值错误可忽略不计，我们使用隐式中点方法的高度准确和一般的八阶组成。该方法的有用性在三氧化氮的立方Jahn-Teller模型和诱导的Renner-Teller-teller-Teller模型中证明了所提出的方法。我们发现，取决于系统，初始状态和采用的准绝化方案，忽略残留耦合可能会导致错误的动态。相比之下，包含残留耦合的精确的准糖哈密顿量的模拟始终产生准确的结果。
Diabatization of the molecular Hamiltonian is a standard approach to removing the singularities of nonadiabatic couplings at conical intersections of adiabatic potential energy surfaces. In general, it is impossible to eliminate the nonadiabatic couplings entirely -- the resulting "quasidiabatic" states are still coupled by smaller but nonvanishing residual nonadiabatic couplings, which are typically neglected. Here, we propose a general method for assessing the validity of this potentially drastic approximation by comparing quantum dynamics simulated either with or without the residual couplings. To make the numerical errors negligible to the errors due to neglecting the residual couplings, we use the highly accurate and general eighth-order composition of the implicit midpoint method. The usefulness of the proposed method is demonstrated on nonadiabatic simulations in the cubic Jahn--Teller model of nitrogen trioxide and in the induced Renner--Teller model of hydrogen cyanide. We find that, depending on the system, initial state, and employed quasidiabatization scheme, neglecting the residual couplings can result in wrong dynamics. In contrast, simulations with the exact quasidiabatic Hamiltonian, which contains the residual couplings, always yield accurate results.
