A simulation study of water property changes using geometrical alteration in SPC/E

• 来源期刊: 中国物理B（英文版）
• 关键词: molecular dynamics simulation geometric modification intermolecular interaction ion's solva-tion
• 年，卷（期）: 2018,（8）
• 页码范围: 214-221
• 页数: 8页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/8/083103

摘要

We present a systematic investigation of the impact of changing the geometry structure of the SPC/E water model by performing a series of molecular dynamic simulations at 1 bar (1 bar = 105 Pa) and 298.15 K. The geometric modification includes altering the H–O–H angle range from 90? to 115? and modifying the O–H length range from 0.90 °A to 1.10 °A inthe SPC/E model. The former is achieved by keeping the dipole moment constant by modifying the O–H length, while in the latter only the O–H length is changed. With the larger bond length and angle, we find that the liquid shows a strong quadrupole interaction and high tetrahedral structure order parameter, resulting in the enhancement of the network structureof the liquid. When the bond length or angle is reduced, the hydrogen bond lifetime and self-diffusion constant decrease due to the weakening of the intermolecular interaction. We find that modifying the water molecular bond length leading to the variation of the intermolecular interaction strength is more intensive than changing the bond angle. Through calculating the average reduced density gradient and thermal fluctuation index, it is found that the scope of vdW interaction with neighbouring water molecules is inversely proportional to the change of the bond length and angle. The effect is mainlydue to a significant change of the hydrogen bond network. To study the effect of water models as a solvent whose geometry has been modified, the solutions of ions in different solvent environments are examined by introducing NaCl. During the dissolving process, NaCl ions are ideally dissolved in SPC/E water and bond with natural water more easily than with other solvent models.