Theoretical prediction of Gruneisen parameter for chalcopyrites

The Gruneisen parameter offers crucial insights into the frequency distribution of the phonon spectrum in solids. In present study, we focus on the theoretical prediction of Gruneisen parameter for magnesium chalcopyrites MgSiP₂, MgSiAs₂, and MgSiSb₂ by using three different logarithmic equation of state (EOS) viz. Poirier Tarantola EOS, Third-Order EOS, and Bardeen EOS at varying compression values (V/V₀). These EOSs are subjected to rigorous testing against the fundamental thermodynamic requirements, especially at extreme compression limits. It is observed that at low compressions, all three EOSs—Poirier Tarantola, Third-Order EOS and Bardeen EOS yield identical results. However, when estimating the Gruneisen parameter at high compression, we found that after compression range V/V₀ = 0.98 for MgSiAs₂ the Poirier Tarantola EOS gets deviated with other two EOSs and also after compression range V/V₀ = 0.99 for MgSiP₂ the Poirier Tarantola EOS gets deviated with other two EOSs and after compression range V/V₀ = 0.99 for MgSiSb₂ the third order EOS get deviated with other two EOS.