Name of UPF PP files: "atomic symbol"."description".UPF

Table of description fields and their meaning
(fields are separated by a dash):

  field 1 (optional)
     rel    = full-relativistic
     starNl =  one core-hole in Nl state
     starhNl= half core-hole in Nl state
        (Nl = 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s 6p)

  field 2
     One among the following
     pz     = Perdew-Zunger (LDA) exch-corr
     vwn    = Vosko-Wilk-Nusair (LDA) exch-corr
     pbe    = Perdew-Burke-Erzerhof (PBE) exch-corr
     blyp   = Becke-Lee-Yang-Parr (BLYP) exch-corr
     pw91   = Perdew-Wang 91 gradient-corrected functional
     tpss   = Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA

  field 3 (optional)
     Any meaningful combination (i.e. sp) of:
     s    = semicore state s in valence
     p    = semicore state p in valence
     d    = semicore state d in valence
     f    = valence f state in core
     n    = nonlinear core-correction

  field 4
     One among the following
     mt    = Martins-Troullier
     bhs   = Bachelet-Hamann-Schlueter and derived
     vbc   = Von Barth-Car (direct fit)
     van   = Vanderbilt ultrasoft
     rrkj  = Rabe Rappe Kaxiras Joannopoulos (norm-conserving)
     rrkjus= Rabe Rappe Kaxiras Joannopoulos (ultrasoft)