高能量短脉冲激光作用水分子的动力学模拟

摘要

Due to the complexity of the experiments for water heated by short pulse and high energy density la -ser , an accurate and simple method is needed to predict the result .Molecular Dynamics is applied to the thermo-dynamic analysis and structure research of water heated by short pulse and high energy density laser .As a result , the temperature of water system increases rapidly with energy added in .Meanwhile , bubbles generate due to the quick diffusion of water .Only 25.5 percent of the energy is used to increase the kinetic energy of water , the rest improves the potential energy .With the increasing of temperature , the thermal motion of water increases , the or-der degree of water reduces continue continuously , the distance of bonding O—H increases, the hydrogen-bond of water weakens and the molecular polarity reduces .%基于高能量短脉冲激光作用水分子实验的复杂性，需用采取一种比较准确且较为方便的方法来预测实验结果是必要的．本文采用分子动力学方法（ Molecular Dynamics ）对高能量密度短脉冲激光加载下的超临界水分子进行热力学分析及结构研究．结果表明，随着能量快速加入加载区域，水分子系统的温度迅速提高．同时，由于分子迅速向四周扩散，在加载区域产生空泡．其中，只有25．5％的能量用以提高水分子系统的动能（温度），其余的能量都用于增大水分子系统的势能（水分子间距）．伴随着温度的提高，水分子热运动加快，有序程度逐渐减弱，O—H间距增加，水分子间的氢键作用减弱，分子极性降低．分子动力学模拟方法研究短脉冲高能量激光对水分子的作用，对水下激光微加工研究有一定指导意义．