[Pw_forum] spin polarization of a organo-metallic compound

[Jia Chen]

Dear Alex,

Thank you for your detailed information. I want to believe plane wave and
gaussian are both good for this type of calculations. And I would be
surprised if the difference really comes from functionals.

For you case, do you have reasons to believe Re pseudopotential is good? If
answers is no, maybe you can try different pseudopotentials for Re. Another
possibility I would consider is the cutoff. Pseudopoentails with d
electrons can be very hard. Sometimes, they need cutoff more than 100Ry. I
don't know the one you are using, but maybe it is a good idea to check. I
am not a big fan of mixing ultra-soft and norm-conserving pseudopotentials,
but maybe it is just my personal taste...

Cheers
Jia


On Thu, Jan 9, 2014 at 1:11 AM, Alex Granov <alex.granov at outlook.com> wrote:

> Dear Giseppe
>
> Thank you very much for your kind attention and the details were said by
> you about spin polarization of such systems.
> I am sorry for the delay to reply your comments. I was doing what proposed
> by you and Stefano to see the difference origin.
>
> so in the following we can see the results obtained:
>
> Quantum -Espresso:
>
> ecutwfc = 70, ecutrho = 600,   (the cutoff has been increased as proposed
> by Stefano)
> Re 186.207  Re.pbe-mt_fhi.UPF
> O  15.999   O.pbe-rrkjus.UPF
> C 12.000    C.pbe-rrkjus.UPF
> H 1.000     H.pbe-rrkjus.UPF
> I 126.90   I.pbe-mt_fhi.UPF
> P  30.9737  P.pbe-mt_fhi.UPF
>
> E=  -312.61421481 Ry (spin-unpolarized)
> E=  -312.66455244 Ry (spin-polarized, total magnetization=4.00 Bohr
> mag/cell
>
>
> Firefly (Quantum Chemistry Code):
>
> B3LYP/6-31++G**:P,C,O,H; LANL2DZ:Re,I  (the system optimized using this
> method)
>
> E (S=0) = -1202.07856 Hartree
> E (S=1) = -1202.06949
> E (S=2) = -1202.04809
>
> B2PLYP/6-31++G**:P,C,O,H; LANL2DZ:Re,I (the energy of previous step was
> modified by adding the MP2 part as proposed by Giseppe)
>
> E (S=0) = -1199.826275 Hartree
> E (S=1) = -1199.825679
> E (S=2) = -1199.820273
>
>
> As still could be seen the plane-wave calculation shows that the
> spin-polarized system is the ground state and quantum chemistry calculation
> using Gaussian-like basis sets shows the trend conversely.
>
>
> -------------------------------------------------
> Alex Granov
> Московский физико-технический институт (MIPT)
> Moscow, Russia
>
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>



-- 
Jia Chen
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