Alkali and alkali-earth elements (simple metals)

For Li (and Be), a standard potential and a potential that treats the $1s$ 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 alkali and alkali-earth elements the semi-core $s$ and $p$ states should be treated as valence states as well. For lighter elements (Na-Ca) it is usually sufficient to treat the the $2p$ and $3p$ states, respectively, as valence states ( _pv), whereas for Rb-Sr the $4s,4p$ and $5s,5p$ states, respectively, must be treated as valence states ( _sv). Hence the standard potentials are (default energy cutoffs are specified as well, but energy cutoff might vary from one release to the other).

H	250
H_h	700
Li	140	Be	300
Li_sv	500	Be_sv	308
Na	100	Mg	210
Na_pv	260	Mg_pv	400
Na_sv	700
K_pv	120	Ca_pv	120
K_sv	260	Ca_sv	270
Rb_pv	120	Sr_sv	230
Rb_sv	220
Cs_sv	220	Ba_sv	190

• Contrary to the common believe, these elements are exceedingly difficult to pseudize
  • in particular in combination with strongly electronegative elements (F) errors can be larger then usual.
  • the present versions are very precise, and should offer a highly reliable description.
• for X_pv pseudopotentials the semi core p states are treated as valence (2p in Na and Mg, 3p in K and Ca etc.)

  for X_sv pseudopotentials, the semi core s states are treated as valence (1s in Li and Be, 2s in Na etc.)