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孙杰 何雅玲 李印实 陶文铨. 水的汽液界面系统中势能与力的EMD模拟研究[J]. 力学学报, 2007, 23(3): 320-324. DOI: 10.6052/0459-1879-2007-3-2006-076
引用本文: 孙杰 何雅玲 李印实 陶文铨. 水的汽液界面系统中势能与力的EMD模拟研究[J]. 力学学报, 2007, 23(3): 320-324. DOI: 10.6052/0459-1879-2007-3-2006-076
Jie Sun, Yaling He, Yinshi Li, Wenquan Tao. EMD simulation study on potential and force at liquid-vapor interface system composed of water molecules[J]. Chinese Journal of Theoretical and Applied Mechanics, 2007, 23(3): 320-324. DOI: 10.6052/0459-1879-2007-3-2006-076
Citation: Jie Sun, Yaling He, Yinshi Li, Wenquan Tao. EMD simulation study on potential and force at liquid-vapor interface system composed of water molecules[J]. Chinese Journal of Theoretical and Applied Mechanics, 2007, 23(3): 320-324. DOI: 10.6052/0459-1879-2007-3-2006-076

水的汽液界面系统中势能与力的EMD模拟研究

EMD simulation study on potential and force at liquid-vapor interface system composed of water molecules

  • 摘要: 分子间势能作用是研究分子界面行为的一个重点所在. 采用平衡态分子动力学模拟(equilibrium molecular dynamics simulation, EMDS)方法,对由水分子构成的汽液界面系统进行了模拟和研究. 分析统计结果符合势能分布在液相区和气相区内存在明显落差的已知结论,并发现不同种力对分子穿越两相区时所起的作用不同,Lennard-Jones(简写L-J)力阻碍分子凝结,而静电力则推动分子凝结并且在合力中起主要作用. 同时,着重对发生相变行为的典型分子进行了追踪和分析,从能量的角度显示了凝结(蒸发)相变过程对应着一个气态(液态)分子由高(低)势能位落入势阱(翻越势垒)的能量降落(抬升)过程.

     

    Abstract: The interaction of potentials between molecules is important for the molecular interface behavior. Theliquid-vapor interface system composed of water molecules is simulated andstudied with equilibrium molecular dynamics (EMD) simulation method in this paper.The results agree with the known conclusions that there is a marked fall ofpotential between the liquid bulk and the vapor bulk. It is also indicatedthat different types of forces have different effects on the moleculesmoving across the interface. The L-J force acts as a resistance tocondensation while the electrostatic force, which is predominant in theresultant force, acts as motivity. Meanwhile, some typical molecules whichparticipate in the phase-change process, are especially traced. The resultsshow that the process of condensation leads to a drop of thepotential energy of a vapor molecule, which falls into the potential well.Correspondingly, the process of evaporation increases thepotential energy of a liquid molecule, which gets over the potentialbarrier.

     

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