# How to watch animation¶

To watch each phonon mode, v_sim is recommended. The file anime.ascii is supposed to work with v_sim version 3.51 or later. An example how to watch phonon modes at a q-point is shown as follows.

First, you need to create a phonopy input file with, e.g., ANIME = 0.5 0.5 0. After running phonopy with this input file, you get anime.ascii that contains all phonon modes at the q-point. Then start v_sim

v_sim anime.ascii


After opening the graphical user interface, you can find a tab called Phonons. There you can see the phonon modes at the q-point that you specified in the phonopy input file. Then select one of the phonon modes and watch by pushing the play button. Because only the unit cell shows up at the start of v_sim, if you want to watch a phonon modulation with a longer period, then change the values of Expand nodes in the Box and symmetry tab (http://inac.cea.fr/L_Sim/V_Sim/user_guide.html#trans). This is especially important when you choose a q-point other than the $$\Gamma$$-point.

V_sim has a good graphical user interface and also a lot of command line options. To read the manual well and to check the command line options help you to use v_sim comfortably, e.g.,

v_sim -w oneWindow anime.ascii -x 1:1:0 -t 0.5:0.5:0.5