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 SiO 2 (α-quartz and stishovite) using first-principle density-functional theory calculations for very high compression up to V /V 0 = 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.

MechElastic: A Python Library for Analysis of Mechanical and Elastic Properties of Bulk and 2D Materials

“…The MechElastic's EOS class contains methods to plot 'Energy vs. Volume' and 'Pressure vs. Volume' curves from energy, pressure and volume data obtained from either calculations or experiments using several fitting models including Vinet, Birch, Murnaghan, and Birch-Murnaghan [40,41,42,43,44,98,97,45,46,99]. As calculations are sensitive to the type of the EOS model, outcomes from multiple models should be carefully examined [100].…”