Structural, Elastic Constant, and Vibrational Properties of Wurtzite Gallium Nitride: A First-Principles Approach

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• 作者：Zahid Usman ; Chuanbao Cao ; Waheed S. Khan ; Tariq Mahmood ; Sajad Hussain ; Ghulam Nabi
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：December 22, 2011
• 年：2011
• 卷：115
• 期：50
• 页码：14502-14509
• 全文大小：836K
• 年卷期：v.115,no.50(December 22, 2011)
• ISSN：1520-5215

文摘

Perdew鈥揥ang 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 (纬_j) of zone-center phonon frequencies are discussed. These phonon calculations calculated at theoretical lattice constants agree well with existing literature.