For elements, potentials which treat the
orbitals
as valence orbitals are available for La, Ce, Ac, Th, Pa U, Np and
Pu. For all elements one standard version and one softer
potential ( _s) is available. Whereas the semi-core
states are always treated as valence states, the
semi-core
states are treated as valence states only in the standard
potentials. For most applications (oxides, sulfides),
the standard version should be used.
For calculations on inter-metallic compounds the soft versions
are however sufficiently accurate.
In addition, special GGA potential are supplied for Ce-Lu, in which
f-electrons are kept frozen in the core (standard model
for the treatment of localised electrons). The number
of f-electrons in the core equals the total number of valence electrons
minus the formal valency. For instance: according to the periodic
table Sm has a total of 8 valence electrons (6 f electrons and 2 s electrons).
In most compounds Sm, however, adopts a valency of 3, hence 5 f electrons are placed
in the core, when the pseudopotential is generated (the corresponding
potential can be found in the directory Sm_3).
The formal valency
is indicted by _n,
where n is either 3 or 2.
Ce
is for instance a Ce potential for trivalent Ce
(for tetravalent Ce the standard potential should be used).