Theoretical Study of Phonon Spectra in Aluminium (Al) and Copper (Cu): Application of Density Functional Theory and Inter – Atomic Force Constant
Theoretical study were used to calculate the dynamical properties of Al and Cu in the FCC structure by using analytical and density functional theory (DFT) within LDA and GGA functional. We calculated phonon frequency and described the results along the X, W, L points of the BZ which were compared with results obtained from analytical, quantum espresso and experimental data.
The results obtained show that the phonon spectra for Cu using analytical method which implements the inter – atomic force constant (IFCs) have been found to be closer to experimental results using 1st – 9th neighbour IFCs with a better percentage error when compared to 1st – 8th neighbour. For Al, LDA underestimates the lattice of about 2.4% while the GGA overestimates it by 0.3%.
Keywords: Phonon, Quantum expresso, Eigen – value, Aluminium (Al), Copper (Cu)