Gruneisen constant

Definition of Guneisen constant

\[\gamma = - \frac{d\ln\omega}{d\ln V} \]

assuming there is only one frequency involved.

Physical significance of Guneisen constant

Usually the Gruneisen constant is positive which implies that when the material is compressed (volume decrease), the oscialltion frequency increases (due to shorter inter atomic distance)

Where did I find this?

I was reading a PHD thesis on high pressure experimentes of rare earth hexaborides, and the author measured the Raman peak shifts under pressure and calculated Gruneissen constant. Gruneisen constant is also mentioned in Huang-Kun's textbook on solid state physics.