水的密度极值和相关性质的分子动力学研究

Molecular dynamics research on density maximum and related properties of water

本文采用分子动力学方法对NVT系综中水的密度极值问题以及分布函数和扩散系数等相关性质进行了模拟.运用极值思想,通过引入新的能量-压力关联判据和线性插值的方法,可以将水的密度极值的温度值点上移到2℃,与实验值更加接近,相对于前人用TIP4P水分子模型的模拟结果-13℃或-23℃具有较好的改进,并且避开了临界点附近统计压力值的困难.模拟获得的径向分布函数和扩散系数的值与实验基本吻合,分子间作用能分布也与文献报道的趋势一致.

The density maximum of water and some related properties such as distribution function and diffusion coefficient were simulated in NVT ensemble by applying molecular dynamics method. By adopting the extremum idea and introducing novel energy-pressure correlation rule and using linear curve fit, we can shift the temperature of density maximum of water up to 2℃, which is more close to the experimental data, and is a good improvement compared to the results - 13℃ or- 23℃ which was obtained by the former researchers using TIP4P water model, additionly it overcomes the difficulty of calculating the pressure near the critical temperature. The simulated radial distribution function and diffusion coefficient also accord with experiment basically, Rather, the pair distribution function is consistent with the literature reported.