We show VBO given by a simple manner.

master_mpi (judge master or not) is added. ves* is written only by master.

We show VBO given by a simple manner (the average of the electrostatic
potential is given by the superpositions of those of atoms.)
This medhod is essentialy similar with the model method given by Van
der Walle and R.Martin. 
[1]C. G. Van de Walle and R. M. Martin, 
“Theoretical study of band offsets at semiconductor interfaces,
” Physical Review B, vol. 35, no. 15, p. 8154, 1987.


NOTE: occupancies (SPEC_ATOM_Q) changes results.
      As long as the total Q of the system is zero, results are meaningful
      It changes atoms which we superpose in order to get the average of the
      electrostatic potential.
      I have not yet find (generally) good choice on SPEC_ATOM_Q.

      I tried; balance of LUMO level by charge transfer;
      sp channels of SPEC_ATOM_Q propotional to ql
      (charge in MT). But they are not necessary good.
Slight modifications. MATERIALS/README.