Mo高压熔化的分子动力学模拟

 采用第一原理方法计算了钼在零温下的结构，表明钼在500 GPa以下一直保持bcc结构（常温），与实验一致。在零压附近计算了E-V关系，利用Murnaghan物态方程拟合得到了零压体积及其模量，与实验结果符合得很好。采用第一原理分子动力学模拟了钼的高压熔化性质。采用NVT系综计算了128个原子的系统，初始构形为bcc结构，体积分别为0.015 48、0.012 19、0.010 98、0.009 84、0.009 10 nm³/atom，计算了几个温度点，拟合得到了熔化曲线，熔化温度明显高于金刚石压砧（DAC）实验结果；将初始构形改变为fcc结构，模拟其熔化特性，得到的熔化温度明显下降，与激光加载DAC实验结果一致，认为可能的原因是钼熔化后形成的液体结构类似于fcc结构，而不是常态时的bcc结构。

Melting Property of Mo at High Pressure from Molecular Dynamics Simulation

Ab initio calculations are performed on Mo to investigate the structure at zero Kelvin, indicating that Mo is stable in a bcc phase up to the pressure of at least 500 GPa. Ab initio molecular dynamics simulations are also performed on Mo to reveal the melting property under high pressure. An NVT (N, number of particles; T, temperature) ensemble at five volumes (V=0.015 48, 0.012 19, 0.010 98, 0.009 84, and 0.009 10 nm³/atom) and N=128 atoms arranged initially in an ideal bcc lattice are used in the simulations. The obtained melting curve is located above the one determined in diamond anvil cell experiments. Change of the initial arrangement to fcc phase leads to the decreasing of melting temperature and approaching of melting curve to that from laser-heating diamond anvil cell experiments. It is possibly revealed that the Mo melt under high pressure is similar to fcc rather than bcc structure at ambient conditions.