# Temperature

This page gives hints on how to compute vibrational free energy, entropy, specific heat, thermal expansion, as well as atomic temperature factors with the ABINIT package.

## Introduction¶

When the phonon band structure and corresponding eigenvectors are known over the whole Brillouin Zone, thanks fo Fourier interpolation (see topic_PhononBands), integrals can be performed, allowing to obtain a wealth of properties, like free energy, entropy, specific heat, as well as atomic temperature factors. For applications of this technique, see [Lee1995].

Moreover, knowing such information for different volumes allows one to compute the thermal expansion, see gruns_ddbs.

The input variables needed to perform the interpolation over the Brillouin Zone are described in topic_PhononBands and are not listed again in the present topic.

compulsory:

basic:

useful:

v2:

## Tutorials¶

• The tutorial Response-Function 2 (RF2) presents the analysis of the DDBs that have been introduced in the preceeding tutorial RF1. The computation of the interatomic forces and the computation of thermodynamical properties is an outcome of this tutorial.