Here, one simple example is given to show what is needed to run a PEtot calculation, and how the input and output files look like. This is to give you a feeling above running PEtot, it is not meant to be the documentation. For detailed documentation, please check the PAR.ETOT package itself. In this example, a 8 atom GaAs cell is calculated. One As atom was deliberately moved from its ideal position, and let the PEtot program to move the atom (num_mov>0 in etot.input) back to its ideal position. To run the PEtot, the maskr file should be kept in the running directory (simply copy it from PAR.ETOT package).