[CPMD-list] Help on creating PSP's...

[Oleg Yazyev]

Hello Reinout,

It is impossible to design pseudopotential with the same nodal
behavior (I mean number of nodes) of PP wavefunctions as AE wavefunctions
possess. The valence (lowest) pseudopotential atomic orbitals
are always nodeless. This is because you have no orthogonality
conditions with core orbitals which are absent in pseudopotential
calculations. The best you can do is to design a hard
pseudopotential which show some oscillating (still being nodeless)
behavior of pseudo wavefunction in the core region.
Treating 3s and 3p states as valence ones you will certainly get
one nodal sphere in 4s and 4p states, but not more.


RD> Dear all,

RD> for testing purposes I am looking to build a (really) hard Germanium
RD> pseudopotential. In particular, the form of the 4p orbitals in the core should
RD> be as accurate as possible.

RD> Currently, I am trying to build such a psp using the Goedecker code (was this a
RD> good idea?), taking the 4s and 4p orbitals as valence orbitals. I try to match
RD> the 4p PSP-wavefunction on the AE-wavefunction mainly by decreasing the values
RD> for rloc and r_l, however the correct nodal behaviour is never achieved. What
RD> goes wrong? Should I treat lowerlying states as valence states to resolve this
RD> problem? Any advice on the matter would be really welcome!

RD> Thanks in advance,

RD> Reinout Declerck



-- 
Best regards,
 Oleg


______________________________________________________
Oleg Yazyev
Ecole Polytechnique Fédérale de Lausanne (EPFL)
Institut des Sciences et Ingénierie Chimiques
CH-1015 Lausanne (Switzerland)
Tel.: +41 21 693 9881
E-mail: oleg.yazyev at epfl.ch
WWW: http://icmbcu001.epfl.ch/yazyev/index.html
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