Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.
J Chem Phys. 2013 Aug 21;139(7):074704. doi: 10.1063/1.4818536.
Grand canonical Monte Carlo (GCMC) and liquid-vapor molecular dynamics (LVMD) simulations are performed to investigate the squeezing and phase transition of a simple liquid argon film confined between two solid surfaces. Simulation results show that the LVMD simulation is capable of capturing the major thermodynamic equilibrium states of the confined film, as predicted by the GCMC simulations. Moreover, the LVMD simulations reveal the non-equilibrium squeeze out dynamics of the confined film. The study shows that the solvation force hysteresis, observed in many surface force experiments, is attributed to two major effects. The first is related to the unstable jumps during the laying transitions of the confined film, in which the gradient of force profile is larger than the driving spring constant. The second effect is related to the squeeze out dynamics of the confined film even though the first effect is absent. In general, these two dynamic processes are non-equilibrium in nature and involve significant energy dissipations, resulting in the force hysteresis.
巨正则蒙特卡罗（GCMC）和液体-蒸气分子动力学（LVMD）模拟被用来研究简单液态氩薄膜在两个固体表面之间的压缩和相变。模拟结果表明，LVMD 模拟能够捕捉到 GCMC 模拟预测的受限薄膜的主要热力学平衡状态。此外，LVMD 模拟揭示了受限薄膜的非平衡挤出动力学。研究表明，在许多表面力实验中观察到的溶剂化力滞后现象归因于两个主要影响。第一个与受限薄膜的铺设转变过程中的不稳定跳跃有关，在这个过程中，力分布的梯度大于驱动弹簧常数。第二个效应与受限薄膜的挤出动力学有关，即使不存在第一个效应。一般来说，这两个动态过程本质上是非平衡的，涉及到大量的能量耗散，导致力滞后。
