First principle calculation of elastic and thermodynamic properties of stishovite

Xun Liu, Xian-Ming Zhou, Zhao-Yi Zeng
2010 Chinese Physics B  
Using ab initio plane-wave pseudo-potential density functional theory method, the elastic constants and band structures of stishovite were calculated. The calculated elastic constants under ambient conditions agree well with previous experimental and theoretical data. C 13 , C 33 , C 44 , and C 66 increase nearly linearly with pressure while C 11 and C 12 show irregularly changes with pressure over 20 GPa. The shear modulus (C 11 -C 12 )/2 was observed to decrease drastically between 40 GPa and
more » ... 50 GPa, indicating acoustic mode softening in consistency with the phase transition to CaCl 2 -type structure around 50 GPa. The calculated band structures show no obvious difference at 0 and 80 GPa, being consistent with the high incompressibility of stishovite. With a quasi-harmonic Debye model, thermodynamic properties of stishovite were also calculated and the results are in good agreement with available experimental data.
doi:10.1088/1674-1056/19/12/127103 fatcat:7klrfumdgjaqxdde2c7y57jsza