Research Centre of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing, People's Republic of China.
J Phys Chem A. 2011 Dec 22;115(50):14502-9. doi: 10.1021/jp207141k. Epub 2011 Nov 23.
Perdew-Wang proposed generalized gradient approximation (GGA) is used in conjunction with ultrasoft pseudopotential to investigate the structural, elastic constant, and vibrational properties of wurtzite GaN. The equilibrium lattice parameters, axial ratio, internal parameter, bulk modulus, and its pressure derivative are calculated. The effect of pressure on equilibrium lattice parameters, axial ratio, internal parameter (u), relative volume, and bond lengths parallel and perpendicular to the c-axis are discussed. At 52 GPa, the relative volume change is observed to be 17.8%, with an abrupt change in bond length. The calculated elastic constants are used to calculate the shear wave speeds in the [100] and [001] planes. The finite displacement method is employed to calculate phonon frequencies and the phonon density of states. The first- and second-order pressure derivative and volume dependent Gruneisen parameter (γ(j)) of zone-center phonon frequencies are discussed. These phonon calculations calculated at theoretical lattice constants agree well with existing literature.
佩德沃德-王提出的广义梯度近似（GGA）与超软赝势相结合，用于研究纤锌矿 GaN 的结构、弹性常数和振动特性。计算了平衡晶格参数、轴比、内参量、体弹模量及其压力导数。讨论了压力对平衡晶格参数、轴比、内参量(u)、相对体积以及与 c 轴平行和垂直的键长的影响。在 52 GPa 时，观察到相对体积变化为 17.8%，键长发生急剧变化。计算得到的弹性常数用于计算[100]和[001]面的剪切波速度。有限位移法用于计算声子频率和声子态密度。讨论了晶心声子频率的一阶和二阶压力导数以及体积相关的格林艾森参数(γ(j))。这些在理论晶格常数下计算的声子与现有文献吻合较好。
