[CPMD-list] Is the label "[GAUSS-HERMITE, KLEINMAN-BYLANDER]" necessary for MT_BLYP ?

[Axel Kohlmeyer]

On Thu, 29 Mar 2007, liu liuxiandong wrote:

LL> Dear all,
LL> 
LL> I saw the input example in the CPMD_tutorial contains the label of
LL> KLEINMAN-BYLANDER for the "O_MT_BLYP.psp". I tried a wavefunction-optimize
LL> test on some water molecules using "O_MT_BLYP.psp" and "H_MT_BLYP.psp"
LL> without any label and the orbital can also converge to 1.0D-7 easily.
LL> The CPMD-manual says that the GAUSS-HERMITE is default. Then how can one
LL> know which label should be needed for a certain MT-type pseudopotential ?

usually you can use both. the major difference is that got GH 
integration you in most cases you have much more computational 
effort, since the number of projectors has to be multiplied with
each integration point. 
the drawback of KB is that the KB separation can lead to unphysically
bound states (ghost states) that depend on the choice of the local
potential and the parameterization of the pseudopotential. please 
check textbooks and the literature for details on that. ghost states
are also discussed in a 'digestable form' in the tutorial paper of 
the fhiPP98 pseudopotential generation package.

cheers,
  axel.

LL> THanks for any suggestion.
LL> 
LL> BEST.
LL> 

-- 
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Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
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