不同水分子模型凝结系数的分子动力学模拟对比研究

采用平衡分子动力学（EMD）方法模拟研究了水的凝结过程，用“特征时间法”统计得到4个不同温度下5种不同水分子模型（SPC、SPCE、TIP3P、TIP4P和TIP5P）的凝结系数．模拟结果表明，不同模型得到的凝结系数都随温度的升高而减小．在相同温度下，凝结系数的统计结果表明：当温度高于400K时，凝结系数按SPCE、TIP4P、TIP3P、SPC、TIP5P模型呈递减趋势，并且TIP4P和TIP3P模型的凝结系数相近；当温度低于400K时，5种模型凝结系数的统计结果相差不大．发现TIP5P模型在温度约高于520K时得不到明显的汽液两相区，无法统计高温下水的凝结系数．

Molecular Dynamics Simulation Study on Condensation Coefficients of Different Potential Models for Water

Equilibrium molecular dynamics(EMD) simulations were carried out in this study to investigate the condensation processes of water.By using characteristic time method,the condensation coefficients for five different types of potential models(SPC,SPCE,TIP3P,TIP4P and TIP5P) were obtained at different temperatures.The results show that the condensation coefficient decreases with the increase of the temperature.When the temperature is higher than 400 K,at the same temperature the descending order of the condensation coefficients for different models is SPCE,TIP4P,TIP3P,SPC and TIP5P,while the difference between the coefficients of TIP4P and TIP3P is tiny.However,when the temperature is lower than 400 K,there are no remarkable differences between the coefficients of the five models at the same temperature.Moreover,the TIP5P can not form the liquid-vapor coexistent region at high temperatures(approximately higher than 520 K),thus the statistic determination for the condensation coefficients fails.