Vibration modes and phonons

Have you set up the local environment?

If not, do that now before proceeding.

Note

For background, see the excellent slide presentation by Andrei Postnikov.

In this set of exercises we will use the method of finite-differences implemented in Siesta to compute force constants in real space. We will explore the cases of a molecule and of a crystal. In the latter case we will focus on the need of a supercell to represent the real-space force constants.

We will also try the visualization tools available.

• Modes of vibration of the benzene molecule
• Phonon dispersion of bulk Si