Structural, elastic constant, and vibrational properties of wurtzite gallium nitride: A first-principles approach

Zahid Usman, Chuanbao Cao*, Waheed S. Khan, Tariq Mahmood, Sajad Hussain, Ghulam Nabi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

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. (Figure presented)

Original languageEnglish
Pages (from-to)14502-14509
Number of pages8
JournalJournal of Physical Chemistry A
Volume115
Issue number50
DOIs
Publication statusPublished - 22 Dec 2011

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