Esser Alexander, Belsare Saurabh, Marx Dominik, Head-Gordon Teresa
Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
The UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, Berkeley, CA, 94720, USA.
Phys Chem Chem Phys. 2017 Feb 15;19(7):5579-5590. doi: 10.1039/c6cp07388c.
We have used the AMOEBA model to simulate the THz spectra of two zwitterionic amino acids in aqueous solution, which is compared to the results on these same systems using ab initio molecular dynamics (AIMD) simulations. Overall we find that the polarizable force field shows promising agreement with AIMD data for both glycine and valine in water. This includes the THz spectral assignments and the mode-specific spectral decomposition into intramolecular solute motions as well as distinct solute-water cross-correlation modes some of which cannot be captured by non-polarizable force fields that rely on fixed partial charges. This bodes well for future studies for simulating and decomposing the THz spectra for larger solutes such as proteins or polymers for which AIMD studies are presently intractable. Furthermore, we believe that the current study on rather simple aqueous solutions offers a way to systematically investigate the importance of charge transfer, nuclear quantum effects, and the validity of computationally practical density functionals, all of which are needed to fully quantitatively capture complex dynamical motions in the condensed phase.
我们使用AMOEBA模型来模拟两种两性离子氨基酸在水溶液中的太赫兹光谱，并将其与使用从头算分子动力学（AIMD）模拟对这些相同体系得到的结果进行比较。总体而言，我们发现可极化力场与甘氨酸和缬氨酸在水中的AIMD数据显示出良好的一致性。这包括太赫兹光谱归属以及将模式特异性光谱分解为分子内溶质运动以及不同的溶质-水交叉相关模式，其中一些模式是依赖固定部分电荷的非极化力场无法捕捉到的。这对于未来模拟和分解更大溶质（如蛋白质或聚合物）的太赫兹光谱的研究来说是个好兆头，目前AIMD研究对这些溶质难以处理。此外，我们认为当前对相当简单的水溶液的研究提供了一种系统地研究电荷转移、核量子效应以及计算上实用的密度泛函的有效性的方法，所有这些都是完全定量捕捉凝聚相中复杂动力学运动所必需的。
