Comparison of spherical cell, OPW, and APW methods for hyperfine contact densities Perdew, J. P. ; Nickerson, S. B. ; Vosko, S. H. ; Moore, R. A. Abstract Publication: Canadian Journal of Physics Pub Date: March 1975 DOI: 10.1139/p75-081 Bibcode: 1975CaJPh..53..648P