CCSE, Japan Atomic Energy Agency (JAEA), 178-4-4, Wakashiba, Kashiwa, Chiba 277-0871, Japan.
Mizuho Information and Research Institute, Inc., 2-3, Kandanishiki-cho, Chiyoda-ku, Tokyo 101-8443, Japan.
J Chem Phys. 2018 Mar 14;148(10):102324. doi: 10.1063/1.5000091.
The isotopologs of liquid water, HO, DO, and TO, are studied systematically by first principles PIMD simulations, in which the whole entity of the electrons and nuclei are treated quantum mechanically. The simulation results are in reasonable agreement with available experimental data on isotope effects, in particular, on the peak shift in the radial distributions of HO and DO and the shift in the evaporation energies. It is found that, due to differences in nuclear quantum effects, the H atoms in the OH bonds more easily access the dissociative region up to the hydrogen bond center than the D (T) atoms in the OD (OT) bonds. The accuracy and limitation in the use of the current density-functional-theory-based first principles PIMD simulations are also discussed. It is argued that the inclusion of the dispersion correction or relevant improvements in the density functionals are required for the quantitative estimation of isotope effects.
通过第一性原理 PIMD 模拟系统地研究了液态水、HO、DO 和 TO 的同位素，其中电子和核的整体实体都被量子力学处理。模拟结果与关于同位素效应的现有实验数据，特别是关于 HO 和 DO 的径向分布峰位移和蒸发能位移，具有较好的一致性。研究发现，由于核量子效应的差异，OH 键中的 H 原子比 OD（OT）键中的 D（T）原子更容易进入离解区，直至氢键中心。还讨论了当前基于密度泛函理论的第一性原理 PIMD 模拟的准确性和使用限制。有人认为，为了定量估计同位素效应，需要在密度泛函中包含色散校正或相关改进。
