For Li (and Be), a standard potential and a potential which treats the shell as valence
states are available ( Li_sv, Be_sv).
For many applications one should use the _sv potential since
their transferability is much improved compared to the standard potentials.
For the other first row elements three pseudopotential versions exist.
For most purposes the standard versions should be used. They work
for cutoffs between 325 and 400 eV, where 370-400 eV are required
to accurately predict vibrational properties, but binding
geometries and energy differences are well reproduced with 325 eV.
The typical bond length errors
for first row dimers (N, CO, O
) are about 1% (compared
to more accurate DFT calculations not experiment).
The hard pseudopotentials _h give results that are essentially identical
to the best DFT calculations presently available (FLAPW, or Gaussian
with huge basis sets).
The soft potentials are optimised to work around 250-280 eV. They
yield very reliable description for most oxides, such
as V
O
, TiO
, CeO
, but fail to describe some structural details
in zeolites (i.e. cell parameters, and volume).