Because they are very "hard", i.e. they require a large number of plane waves to give meaningful results. (this comes from the fact that atomic d orbitals have a small orbital radius and from the fact that - for an equal value of the orbital radius - orbitals with a larger angular monentum require a larger number of plane waves to be represented). If you are ready to pay the price of a very large kinetic-energy cutoff for your basis set, there is nothing wrong in using norm-conserving PP's. Hope this clarifies. Stefano Baroni
Noah_Park wrote: > Dear All; > (Especially to Eyvaz) > Let me ask you a rather physical question deviated from the code. > > Why the application of Norm-Conserving PseudoPotential is doubtable in the > cases of transition metal ? > Could anybody answer me or guide a reference that I should read ? > > Best regards, > > Noah > > > applicability of NC PsP to transition metals is a horse of another color. > > There is no doubt that in this case US PsP works well. > > > > Regards, > > Eyvaz Isaev, PhD > > Theoretical Physics Department > > Moscow Steel and Alloys Institute > > >?????j)b? b???~????,q?+?m????^??+??,???j)fj????b?????rum= >
