[Pw_forum] choice of the pseudo, Ni(110)

[Cyrille Barreteau]

The choice of exchange-correlation functional is
not an easy task. As a rule of thumb I would say
that GGA is better for 3d metals while LDA
is better for 5d. And 4d is in between..
For example LDA  leads to the wrong magnetic
behaviour of Iron (mainly because the lattice
constant found in LDA is too small).
But if you look at surface energies of Pt
you will find anormally low values in GGA...
But maybe people  looking at interaction of
molecules with a Pt surface would find GGA
better......
It is a kind of cookery:-)

   cyrille


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On Mar 22 février 2005 18:55, Paolo Giannozzi a écrit :
> On Tuesday 22 February 2005 16:17, Varki Pagan (Peressi) wrote:
>
>> first used pseudo : [...]
>>           Perdew-Zunger (LDA) exch-corr
>> [...] obtaining a0 = 6.47 alat and Emin =  -85.72192 Ry
>
>> second used pseudo : [...]
>>           Perdew-Burke-Ernzerhof (PBE) exch-corr
>> [...] obtaining a0 = 6.66 alat and Emin = -85.89509 Ry
>
> "different exchange-correlation" is something more than simply
> "different pseudos". It is well known that gradient-corrected
> functionals (like PBE) tend to yield larger equilibrium lattice
> parameters than LDA.
>
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> Paolo
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