Lattice Dynamics in Some FCC Metals: Application of Phonon Dispersions in Nickel (Ni) and Platinium (Pt)
The computational theoretical investigation of lattice dynamics induced by phonon – electrons interactions were carried out in some FCC metals; Ni and Pt to 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.
Frequency calculations of the 1- 9NN for Pt, and 1-6NN for Ni using inter – atomic force constant (IFCs) approach, the results obtained are reasonably close to experimental results which are available in the literature. We also observed smaller values of force constants for neighbours higher than the fourth neighbour. The computational lattice error of the LDA in Ni was – 2.7% and this was corrected to 0.2% using the GGA while the lattice constant of Pt was overestimated by 0.1% and this was also corrected to 2.1% by GGA. In Nickel the phonons of the IFCs predict well the experimental phonons than those from quantum espresso code.
We also employed the nineth (1-9NN) neighbour force constant to elucidate the nature of phonon diagrams of Pt while the first to sixth neighbour force constant has been employed to calculate the phonon diagrams of Ni analytically.
Keywords: Phonon, Nickel (Ni), Platinum (Pt), Quantum expresso, Eigen – value