碘化钠弹性常数和声速的量子力学从头算

Ab initio calculations of elastic constants and sound velocity of sodium iodine

采用从头算平面波赝势（PWP）方法结合电子交换关联能的广义梯度近似（GGA）理论,对不同压力下碘化钠的晶体结构进行几何优化计算,得到体系的最稳定优化构型和相应的能量,利用胡克定律计算得到了相应压力下的弹性性质,取得了碘化钠单晶在零温条件下、压力0～30 GPa范围内弹性常数与压力的关系.根据弹性波在晶体中的传播行为求解了碘化钠单晶[100]、[110]、[111]三个主要方向的声速.

The optimization of the crystal structure of sodium iodine under various pressure are made with application of the plane wave pseudopotential （PWP） and generalized gradient approximation （GGA） in ah initio calculation. The stable structure and its system total energy are obtained for single crystal sodium iodine at 0 K. From the energy consideration and Hooke＇s law, the elastic constants and bulk modulus with pressure up to 30 GPa are displayed, in addition to the sound velocities in the three principal propagation directions of [1001.,[1101 and [111].