<pre> get_psp(self, sym=None, z=None) get the pseudopotential filename from the psp database

:Parameters:

sym : string the chemical symbol of the species

z : integer the atomic number of the species

you can only specify sym or z. Returns the pseudopotential filename, not the full path.

get_psp_nuclear_charge(self, psp) get the nuclear charge of the atom from teh psp-file.

This is not the same as the atomic number, nor is it necessarily the negative of the number of valence electrons, since a psp may be an ion. this function is needed to compute centers of ion charge for the dipole moment calculation.

We read in the valence ion configuration from the psp file and add up the charges in each shell.

get_psp_valence(self, psp) get the psp valence charge on an atom from the pspfile.

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