从头算方法研究面心立方铝在高温高压下的热力学状态方程

Ab initio simulation on thermodynamic equation of state of fcc aluminum under high temperature and pressure

用从头算方法优化计算了面心立方铝的电子结构和总能,得到了它在零温下的状态方程和弹性性质.将得到的总能与晶格体积拟合到Debye模型,获得了非平衡态下的Gibbs自由能与温度、压力之间的关系,在此基础上计算了相应的热状态方程,利用Burakovsky-Preston-Silbar(BPS)熔化模型计算了铝的熔化曲线.所有的电子结构和总能计算都是基于局域密度近似(LDA)和广义梯度近似(GGA)的平均得到的.计算得到的铝在高温、高压下的状态方程与一些热力学性质和熔化曲线同冲击波和静高压实验数据在225GPa压力范围内符合良好.

The ab initio electronic structure optimization and total-energy calculations are used to study the equation of state （EOS） and elastic properties of fcc aluminum at zero temperature. We use the calculated energy of a solid as a function of the molecular volume fitting to the quasi-harmonic Debye model to obtain the non-equilibrium Gibbs function, then to derive the thermal equation of state （EOS） of the corresponding phase. The melting curve at different pressures is presented based on the Burakovsky-Preston-Silbar （BPS） model. All total-energy calculations are based on the average of local density approximation （LDA） and general gradient approximation （GGA）. The results show that the calculated EOS and pressure dependence of thermodynamics and melting curve are in good agreement with the shock compression and the diamond-anvil-cell （DAC） data within a wide range of pressure up to 225 GPa.