Semiclassical Molecular Dynamics in Extended Systems

阿帕卡里安是由理论和计算化学计划的拨款支持，以执行半经典分子动力学模拟的量子动力学效应的扩展系统。这种方法已经被开发并成功地应用于气相光谱分析。这种方法现在被应用于低温固体、凝聚氢和氢键网络的光谱，以及室温液体共振拉曼光谱和光子回波光谱。量子效应用一个只依赖于输入势能参数的‘黑盒’来模拟。由于这些应用的自由度较多，计算量非常大。这可以通过依赖于通过重复的蒙特卡罗采样进行波函数重建的短时传播来部分补救。为了理解液体和固体等高维系统中的量子动力学，需要新的模拟方法。特别是在凝聚相光谱学中，将可观测值与潜在的分子结构及其运动联系起来目前依赖于近似技术。旨在从微观上理解凝聚相光谱的理论发展是解释和设计实验的宝贵工具。

V. Ara Apkarian is suported by a grant from the Theoretical and Computational Chemistry Program to perform semiclassical molecular dynamics simulations of quantum dynamic effects in extended systems. This approach has already been developed and employed successfully for gas-phase spectroscopy. The methodology is now being applied to the spectroscopy of cryogenic solids, condensed hydrogen, and hydrogen-bonded networks, as well as room-temperature liquid resonance-Raman and photon-echo spectroscopies. Quantum effects are simulated with a `black box` dependent only on inputted potential energy parameters. Due to the many degrees of freedom in these applications, the computations are very intensive. This is partially remedied by relying on short-time propagation with wavefunction reconstruction through repeated Monte Carlo sampling. In order to understand quantum dynamics in systems of large dimensionality, such as liquids and solids, new simulation methods are needed. In condensed phase spectroscopy in particular, connecting observables to the underlying molecular structures and their motions currently relies on approximate techniques. Theoretical developments that aim toward a microscopic understanding of condensed phase spectra are invaluable tools in the interpretation and design of experiments.