Trenins George, Haggard Christopher, Althorpe Stuart C
Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland.
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
J Chem Phys. 2022 Nov 7;157(17):174108. doi: 10.1063/5.0129482.
We describe improvements to the quasicentroid molecular dynamics (QCMD) path-integral method, which was developed recently for computing the infrared spectra of condensed-phase systems. The main development is an improved estimator for the intermolecular torque on the quasicentroid. When applied to qTIP4P/F liquid water and ice, the new estimator is found to remove an artificial 25 cm red shift from the libration bands, to increase slightly the intensity of the OH stretch band in the liquid, and to reduce small errors noted previously in the QCMD radial distribution functions. We also modify the mass-scaling used in the adiabatic QCMD algorithm, which allows the molecular dynamics timestep to be quadrupled, thus reducing the expense of a QCMD calculation to twice that of Cartesian centroid molecular dynamics for qTIP4P/F liquid water at 300 K, and eight times for ice at 150 K.
我们描述了对准质心分子动力学（QCMD）路径积分方法的改进，该方法是最近为计算凝聚相系统的红外光谱而开发的。主要进展是对准质心上分子间扭矩的一种改进估计器。当应用于qTIP4P/F液态水和冰时，发现新的估计器消除了来自摆动带的25厘米人为红移，略微增加了液体中OH伸缩带的强度，并减少了先前在QCMD径向分布函数中发现的小误差。我们还修改了绝热QCMD算法中使用的质量缩放，这使得分子动力学时间步长可以增加到四倍，从而将QCMD计算的成本降低到300K时qTIP4P/F液态水笛卡尔质心分子动力学成本的两倍，150K时冰的成本的八倍。
