[Pw_forum] Choice of pseudpotential (d orbitals for Fe)

[Nicola Marzari]

Dear Cristian,


you might also want to have a look at some of our recent literature
arguing the relevance of GGA+U for these complexes (a 2006 PRL and a JCP
2007).

On the pwscf website we uploaded an ultrasoft Fe with 16 valence 
electrons that was generated in a 2.5+ oxidation state, to more closely
mimic usual conditions in these complexes. Our experience was that is
was performing sligtly better than the other PBE ultrasoft 16e on the
site, but overall with fairly similar results.

				nicola


Cristian Degli Esposti Boschi wrote:
> Dear users and developers,
> 
> I'm using Quantum Espresso 3.2 and would like to reproduce some of the DFT results
> of C. Rovira et al., J. Phys. Chem. A 101, 8914 (1997) regarding the
> equilibrium geometries of Iron-Porphyrin (FeP) complexes.
> However, I find some significant discrepancies:
> in particular in our equilibrium structure of FeP(Im)(CO), where Im denotes the
> imidazole group, the FeP plane gets considerably more "domed" with respect
> to what reported in the above-mentioned reference.
> 
> Of course there could be several reasons for this, but in particular
> I noted that they use XC functional of Becke (exchange) and Perdew (corr)
> type. They also mention a comparison with BLYP-type functionals.
> However, since orbital energy structure of the ground state
> involves d orbitals of Fe, initially I chose the pseudopotentials
> (in the pwscf site) that include the d orbitals contribution,
> namely
> 
> Fe.pbe-nd-rrkjus.UPF or
> Fe.pz-nd-rrkjus.UPF
> 
> For the sake of uniformness I used PBE- or PZ-type pseudopotentials also for C, O and N.
> 
> Now, I wonder if the problem of excessive doming could be due to the use
> of wrong pseudopotential ... 
> I would like to try with BLYP's but the one for Fe
> does not seem to include explicitly d orbitals. Are there other sources
> of pseudopotentials?
> 
> Thanks in advance for any help. Cristian
> 
> ___________________________________________________
> Cristian Degli Esposti Boschi
> CNR, CNISM, Unita' di Ricerca di Bologna, c/o
> Dipartimento di Fisica, Universita' di Bologna
> viale Berti-Pichat, 6/2, 40127, Bologna, Italia
> tel. ++39 051 2095114   fax ++39 051 2095113
> e-mail: cristian.degliesposti -AT- unibo.it
> web:    http://www.df.unibo.it/fismat/theory
> ___________________________________________________
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Prof Nicola Marzari   Department of Materials Science and Engineering
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