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首页> 外文期刊>The Journal of Chemical Physics >Sampling the thermal Wigner density via a generalized Langevin dynamics
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Sampling the thermal Wigner density via a generalized Langevin dynamics

机译：通过广义的Langevin动力学对热滑动密度进行采样

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摘要

The Wigner thermal density is a function of considerable interest in the area of approximate (linearized or semiclassical) quantum dynamics where it is employed to generate initial conditions for the propagation of appropriate sets of classical trajectories. In this paper, we propose an original approach to compute the Wigner density based on a generalized Langevin equation. The stochastic dynamics is nontrivial in that it contains a coordinate-dependent friction coefficient and a generalized force that couples momenta and coordinates. These quantities are, in general, not known analytically and have to be estimated via auxiliary calculations. The performance of the new sampling scheme is tested on standard model systems with highly nonclassical features such as relevant zero point energy effects, correlation between momenta and coordinates, and negative parts of the Wigner density. In its current brute force implementation, the algorithm, whose convergence can be systematically checked, is accurate and has only limited overhead compared to schemes with similar characteristics. We briefly discuss potential ways to further improve its numerical efficiency.
机译：Wigner热密度是在近似（线性化或半导体）量子动态领域相当兴趣的函数，其中用于为适当的古典轨迹组传播的初始条件而产生初始条件。在本文中，我们提出了一种原始方法来基于广义Langevin等式计算Wigner密度。随机动力学是不值的，因为它包含坐标依赖性摩擦系数和耦合动量和坐标的广义力。通常，这些数量通常不知道，并且必须通过辅助计算估计。新采样方案的性能在标准模型系统上测试，具有高度非生物特征，如相关的零点能量效应，动量之间的相关性和坐标之间的相关性，以及Wigner密度的负部分。在其当前的蛮力实现中，可以系统地检查其收敛的算法，是准确的，并且与具有相似特性的方案相比，只有有限的开销。我们简要讨论了进一步提高其数值效率的潜在方法。

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