TY - JOUR

T1 - Structural, elastic constant, and vibrational properties of wurtzite gallium nitride

T2 - A first-principles approach

AU - Usman, Zahid

AU - Cao, Chuanbao

AU - Khan, Waheed S.

AU - Mahmood, Tariq

AU - Hussain, Sajad

AU - Nabi, Ghulam

PY - 2011/12/22

Y1 - 2011/12/22

N2 - 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)

AB - 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)

UR - http://www.scopus.com/inward/record.url?scp=84055187670&partnerID=8YFLogxK

U2 - 10.1021/jp207141k

DO - 10.1021/jp207141k

M3 - Article

AN - SCOPUS:84055187670

SN - 1089-5639

VL - 115

SP - 14502

EP - 14509

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 50

ER -