Systematic study of the influence of different equations of states on the calculation of elastic properties^†

Abstract

In order to test the influence of the choice of the equation of states (EOS) on the elastic properties we calculated the energy–volume dependence for AlN (rocksalt and wurtzite) and SiO₂ (α-quartz and stishovite) using first-principle density-functional theory calculations for very high compression up to V/V₀=0.58. We then used the same data, but using different ranges of the data, to fit seven different EOS. In particular, we compare the behavior of Murnaghan EOS, Birch-Murnaghan third- and fourth-order EOS, natural strain third and fourth order, the universal EOS by Vinet and an EOS with a polynomial E–V relation proposed by Teter et al. under high compression.

• AlN
• SiO₂
• equation of state
• density-functional theory
• elastic properties

Acknowledgements

C.L. and J.K. would like to thank the Dr Erich-Krüger foundation as well as the DFG within SPP 1236: Synthesis, In Situ Characterisation and Quantum Mechanical Modelling of Earth Materials, Oxides, Carbides and Nitrides at Extremely High Pressures and Temperatures for financial support. Furthermore, we would like to thank the ZIH Dresden for computational time and support.