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

[Cristian Degli Esposti Boschi]

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

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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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