According to http://www.emsl.pnl.gov/docs/nwchem/nwchem-support/2006/02/0054.RE:_NWCHEM_New_NWPW_features_in_NWChem_4, alpha corresponds to the width of the Lorentzian function. Can anyone tell me the purpose of varying this width? My initial guess would be that it is used to model the bulk DOS from that obtained from the unit cell.