Vasp is a python wrapper which hides from the user all the dreary file manipulation and grepping that working with scientific codes generally imply. It is initialized as follows:
>>> from pylada.vasp import Vasp
>>> vasp = Vasp()
>>> vasp.add_specie = 'Si', '/path/to/directory/Si'
>>> vasp.add_specie = 'Ge', '/path/to/directory/Ge'
We will get to the details below, but suppose that we already have some silicon-germanium structure. Then launching the calculation and retrieving the gap is as complicated as:
>>> result = vasp(structure, ispin=2)
>>> print "Success?", result.success
True
>>> print result.eigenvalues
array([-5, -6., -7]) * eV
This will launch vasp in the current directory and wait until the calculation is finished. We then check whether the calculations completed and print the eigenvalues. The latter are a numpy array, signed with the appropriate units. Since they are a python object, it is easy to create more complex post-processing.