Abstract
Expressions are derived for two dimensionless first order Gruneisen parameters lambda =V/ gamma ( delta gamma / delta V)T and mu =T/ gamma ( delta gamma / delta T)V which gives the volume and temperature variation of Gruneisen constant gamma respectively. A modified expression is derived for the compressibility of the crystal in which the effect of the lambda parameter is included. It is further shown that the Gruneisen's relation, which gives an expression for the coefficient of thermal expansion, contains an additional term that depends on mu parameter. Therefore the variation of the Gruneisen constant when the temperature and volume of the crystal changes is obtained directly from the equation of state in the case of copper, silver and gold. This variation is in excellent agreement with the corresponding change obtained by using the parameters lambda and mu .