Phonon Dispersion Relation of Lead (Pb) and Palladium (Pd)

Abstract

The Computational theoretical techniques was applied in the investigation of Phonon Dispersion of Lead (Pb) and Palladium (Pd).

The first principle technique which make use of the density functional theory as implemented by quantum expresso as well as inter–atomic force constant (IFC) techniques (Born-von Jarman) which was extended to higher number of neighbours than what is available in the literature were employed in this research.

The results obtained shows that the local density approximation (LDA) phonon dispersion slightly overestimates experimental results whereas the generalized gradient approximation (GGA) gives slightly lower frequency. However, there was negligible improvement in the quality of fit in lead when the ninth neighbour (1 - 9NN) interaction were introduced.