Communication: On the consistency of approximate quantum dynamics simulation methods for vibrational spectra in the condensed phase.
Communication: On the consistency of approximate quantum dynamics simulation methods for vibrational spectra in the condensed phase.
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DOI：
10.1063/1.4901214
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
M. Rossi;Hanchao Liu;F. Paesani;J. Bowman;M. Ceriotti
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文献类型：
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作者：
M. Rossi;Hanchao Liu;F. Paesani;J. Bowman;M. Ceriotti
包括量子力学对凝聚相中原子核动力学的影响是具有挑战性的，因为精确方法的复杂性随着量子自由度的数量呈指数增长。规避这些限制的努力可以追溯到两种方法：用严格的量子力学处理一小部分自由度的方法，将系统的其余部分视为静态或经典环境，以及用量子力学处理整个系统的方法，但使用近似动力学。在这里，我们进行了系统的比较，这两种哲学之间的描述量子效应的振动光谱，嵌入本地MPEG4模型和混合量子经典模型作为第一家庭的方法的代表，质心分子动力学和恒温环聚合物分子动力学作为后者的例子。我们使用作为基准D2 O掺杂HOD和纯H2O在三个不同的热力学状态点（冰Ih在150 K，和液体在300 K和600 K），建模与简单的q-TIP 4P/F势能和偶极矩表面。除了少数例外，不同的技术产生的红外吸收频率在几十厘米（-1）内彼此一致。与经典分子动力学的比较表明了核量子效应在最高温度下的重要性，并且详细讨论了各种方法之间的差异，让我们得出一些关于它们所基于的非常不同的近似的影响的（间接）结论。这种完全不同的方法之间的交叉验证可能表明一种方法，以进一步提高凝聚相量子动力学模拟的最新技术水平。
Including quantum mechanical effects on the dynamics of nuclei in the condensed phase is challenging, because the complexity of exact methods grows exponentially with the number of quantum degrees of freedom. Efforts to circumvent these limitations can be traced down to two approaches: methods that treat a small subset of the degrees of freedom with rigorous quantum mechanics, considering the rest of the system as a static or classical environment, and methods that treat the whole system quantum mechanically, but using approximate dynamics. Here, we perform a systematic comparison between these two philosophies for the description of quantum effects in vibrational spectroscopy, taking the Embedded Local Monomer model and a mixed quantum-classical model as representatives of the first family of methods, and centroid molecular dynamics and thermostatted ring polymer molecular dynamics as examples of the latter. We use as benchmarks D2O doped with HOD and pure H2O at three distinct thermodynamic state points (ice Ih at 150 K, and the liquid at 300 K and 600 K), modeled with the simple q-TIP4P/F potential energy and dipole moment surfaces. With few exceptions the different techniques yield IR absorption frequencies that are consistent with one another within a few tens of cm(-1). Comparison with classical molecular dynamics demonstrates the importance of nuclear quantum effects up to the highest temperature, and a detailed discussion of the discrepancies between the various methods let us draw some (circumstantial) conclusions about the impact of the very different approximations that underlie them. Such cross validation between radically different approaches could indicate a way forward to further improve the state of the art in simulations of condensed-phase quantum dynamics.