Comparing research on the pressure or volume dependence of Gruneisen parameter

Three relations for the pressure or volume dependence of Gruneisen parameter have been reported in literatures by Fang, Nie, and Cui one after another. The validities of these relations are tested on NaCl in the range of pressure 0-30GPa and at 300K in this paper. It is shown that the calculated results given by the three equations are all in good agreement with Birch's experimental data at low pressures, but at high pressures, the differences between them increase with the increasing pressures. As far as the three relations are concerned, the one presented by Nie is better