Volume dependence of the Grüneisen parameter for MgO

Unified analyses for P – V – T equations of state of MgO recently presented by several workers in order to obtain a solution for pressure-scale problems in high P – T experiments make use of a new functional form for volume dependence of the Grüneisen parameter. In the present study we point out that this formulation is not consistent with variation of the third order Grüneisen parameter with the change in pressure. We have emphasized that the Stacey–Davis formulation for the volume dependence of the Grüneisen parameter is more appropriate than the other functional form used in the recent literature. The results have been obtained and reported for the volume dependence of the Grüneisen parameter and its higher order derivatives.