论文标题
用于非绝热动力学的部分线性化旋转映射方法。 ii。与相关方法的分析和比较
A partially linearized spin-mapping approach for nonadiabatic dynamics. II. Analysis and comparison with related approaches
论文作者
论文摘要
在上一篇论文中[J。 R. Mannouch和J. O. Richardson,J.〜Chem。该方法使用旋转映射空间中的Stratonovich-Weyl方法描述了与前向和向后电子路径积分相关的动力学。尽管这是部分线性化的自旋映射方法的第一个示例,但已知完全线性的自旋映射能够合理地准确地重现一系列非绝热模型系统的动力学可观察物。在这里,我们对Spin-PLDM的实时量子相关函数和完全线性化的自旋映射的实时量子相关函数进行了详尽的比较,以确定两种方法的相对准确性。特别是,我们表明Spin-PLDM在其实时相关函数的定义中包含一个附加术语,这减少了许多已知误差,这些错误无处不在,这些误差无处不在。部分线性化方法比其完全线性化的对应物的优点是,可以通过在中间时间重新采样映射变量来系统地改进结果。我们为Spin-PLDM提供了这样的方案,并表明,对于经典核的近似值的系统,仅使用几个“跳跃”就可以获得数值确切的结果。此外,我们实施了Spin-PLDM方法的重点初始条件,这减少了为了达到动态数量收敛所需的经典轨迹的数量,而结果的准确性似乎很小。
In the previous paper [J. R. Mannouch and J. O. Richardson, J.~Chem.~Phys.~xxx, xxxxx (xxxx)] we derived a new partially linearized mapping-based classical-trajectory technique, called spin-PLDM. This method describes the dynamics associated with the forward and backward electronic path integrals, using a Stratonovich-Weyl approach within the spin-mapping space. While this is the first example of a partially linearized spin mapping method, fully linearized spin mapping is already known to be capable of reproducing dynamical observables for a range of nonadiabatic model systems reasonably accurately. Here we present a thorough comparison of the terms in the underlying expressions for the real-time quantum correlation functions for spin-PLDM and fully linearized spin mapping in order to ascertain the relative accuracy of the two methods. In particular, we show that spin-PLDM contains an additional term within the definition of its real-time correlation function, which diminishes many of the known errors that are ubiquitous for fully linearized approaches. One advantage of partially linearized methods over their fully linearized counterparts is that the results can be systematically improved by re-sampling the mapping variables at intermediate times. We derive such a scheme for spin-PLDM and show that for systems for which the approximation of classical nuclei is valid, numerically exact results can be obtained using only a few `jumps'. Additionally, we implement focused initial conditions for the spin-PLDM method, which reduces the number of classical trajectories that are needed in order to reach convergence of dynamical quantities, with seemingly little difference to the accuracy of the result.