Phonon spectra and temperature variation of bulk properties of Cu, Ag, Au and Pt using Sutton–Chen and modified Sutton–Chen potentials

Abstract

Three potentials of the Finnis–Sinclair type are studied with regard to their suitability for predicting bulk thermal and elastic properties of fcc metals Cu, Ag, Au and Pt over a wide temperature range. We start with a particular parametrization of the Finnis–Sinclair model known as the Sutton–Chen potential and a later version of the same, known as the quantum Sutton–Chen potential. The quasiharmonic lattice dynamics method is used to study the temperature variation of the thermodynamic properties. Both models are found to yield poor results for thermal expansion, which can be traced to rapid softening of transverse phonon frequencies with increasing lattice parameter. The form of the Sutton–Chen potential is modified here to seek improvement in the agreement between quasiharmonic calculations and experimental data. It is found that the modified potential better predicts bulk properties in nearly all cases studied. Significant improvement is seen over the Sutton–Chen potential, while lesser but still substantial improvement is observed over the Quantum-Sutton Chen potential.