A comment on the paper A method of calculating volume dependence of second and third order Gruneisen parameters for MgOby S. Chandra, Physica B 643 (2022) 414185

Different models recently used by Chandra (Physica B 643 (2022) 414185) for the volume dependence of Gruneisen parameter of MgO yield results for the third order Gruneisen parameter which are not consistent with the thermodynamic constraint at extreme compression. The results for the third order Gruneisen parameter lambda at zero-pressure can not be less than its value at extreme compression. The finding by Chandra that lambda increases with the increase in pressure is in contradiction with the results determined from fundamental studies based on the seismic data. The earlier investigations reveal that lambda decreases with the increase in pressure.

Automated summary

The recent models used by Chandra for the volume dependence of the Gruneisen parameter of MgO yield inconsistent results for the third order Gruneisen parameter, which contradicts the thermodynamic constraint at extreme compression. Chandra's finding that the parameter increases with pressure is in contradiction with earlier studies based on seismic data, which showed a decrease with increasing pressure.