The properties of molecules and materials containing light nuclei are affected by their quantum mechanical nature. Accurate modeling of these quantum nuclear effects requires computationally demanding path integral techniques. Considerable success has been achieved in reducing the cost of such simulations by using generalized Langevin dynamics to induce frequency-dependent fluctuations. Path integral generalized Langevin equation methods, however, have this far been limited to the study of static, thermodynamic properties due to the large perturbation to the system’s dynamics induced by the aggressive thermostatting. Here, we introduce a post-processing scheme, based on analytical estimates of the dynamical perturbation induced by the generalized Langevin dynamics, which makes it possible to recover meaningful time correlation properties from a thermostatted trajectory. We show that this approach yields spectroscopic observables for model and realistic systems that have an accuracy comparable to much more demanding approximate quantum dynamics techniques based on full path integral simulations.

中文翻译：

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使用路径积分广义Langevin方程恒温器对量子动力学进行廉价建模

包含轻核的分子和材料的性质受其量子力学性质的影响。这些量子核效应的精确建模需要计算上要求严格的路径积分技术。通过使用广义Langevin动力学引起频率相关的波动，在降低此类仿真的成本方面已经取得了相当大的成功。然而，路径积分广义Langevin方程方法由于积极的恒温作用而对系统动力学产生较大的扰动，因此至今仅限于静态，热力学性质的研究。在这里，我们介绍了一种后处理方案，该方案基于对由广义Langevin动力学引起的动力学扰动的解析估计，这使得可以从恒温轨迹中恢复有意义的时间相关特性。我们表明，该方法可为模型和现实系统提供光谱可观观测值，其准确度可与基于全路径积分模拟的更为苛刻的近似量子动力学技术相媲美。