Phonon spectrum of AlN

The PHONON spectrum of Wurtzite AlN is calculated from first principles. PHONON automates all steps needed to derive the dispersion relation for the full Brillouin zone, the Phonon density of states and thermodynamic functions like internal energy, entropy, specific heat and free energy.

The following steps are performed automatically by PHONON:

1. Creation of a supercell suitable for the calculation of the interatomic forces

2. Setup of displacement models needed to calculate forces

3. Symmetry analysis for displaced structure models

4. Identification of Raman/IR active modes

5. Computation of forces Construction of force constant matrix and dynamical matrix

6. Computation of phonon dispersion relation and density of states

7. Derivation of thermodynamic functions

Tasks:

PHONON:

1. The calculated phonon dispersion curves agree to 0.2 THz with inelastic X-ray and neutron scattering data

2. Thermodynamic functions like the entropy of the system, the heat capacity and the free energy are readily available from the MedeA-Phonon output.

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References:

1. K. Parlinski, Z. Q. li, Y. Kawazoe, Phys rev. lett. 78, 4063

2. Inelastic X-ray scattering: M. Schwoerer-Böhning, A. T. Macrander, M. Pabst, P. Pavone, Phys. Status Solidi (b) 215, 177 (1999)