*****  Na_VDB_LDA_SEMI from CPMD
Ultrasoft Na with 2s and 2p states in valence
Info by Axel Kohlmeyer:

   the sodium potential is an adapted version of the LDA
   potential in the vanderbilt library, but tweaked to 
   remove one small flaw (negative density) and to be
   compatible with CPMD which (for historic reasons?) needs 
   the same number of projectors for each angular momentum.
   this has been tested on bulk sodium and gives again excellent
   agreement with other codes/potentials.