[Pw_forum] spin polarization of a organo-metallic compound
Jia Chen
jiachenchem at gmail.com
Fri Jan 3 23:05:48 CET 2014
Dear Giuseppe,
It is very nice of you to provide so much information! It is certainly much
more to this question than I thought earlier. Thank you very much and Happy
New Year.
Cheers
Jia
On Fri, Jan 3, 2014 at 4:27 PM, Giuseppe Mattioli <
giuseppe.mattioli at ism.cnr.it> wrote:
>
> Dear Jia
> Sorry, I'm not at my usual desktop, and I cannot therefore access to
> the whole of my data base. But I can recall by heart this paper
> Scherlis, Cococcioni, Sit and Marzari; J. Phys. Chem. B 2007, 111,
> 7384-7391
> which investigates the spin states of the well known iron(II)
> porphyrin and of some of its (Fe(II) and Fe(III)) derivatives. In that
> case a tendency to stabilize lower-spin states is reported (i.e. in
> the case of the imidazole or chloride ligated molecules triplet and
> quartet states arise at the b3lyp level, respectively, as opposite to
> the expected quintet and sextet states. I've performed calculations
> (partly unpublished, partly published here,that is, actually, not very
> visible...)
> Macroheterocycles 2011 4(3) 161-163
> on different mono and di-iron porphyrin and phthalocyanine complexes.
> For instance, in the case of the Fe(III) azide and chloride porphyrins
> I've obtained a sextet spin-state in the case of DFT+U(Fe=4.0 eV, with
> Quantum ESPRESSO) and B2PLYP/def2-TZVPP (with the ORCA package), and a
> quartet spin-state in the case of B3LYP/def2-TZVPP (always with ORCA).
> More examples: there is an interesting family of Co(III) complexes
> investigated by several authors (including me). You can find several
> structures in the supporting information of
> Li and Siegbahn; J. Am. Chem. Soc. 2013, 135, 13804−13813
> In the case of the tetranuclear Co(III) complex both B3LYP and
> DFT+U(Co=5.9 eV,O=2.0 eV) indicate a low spin (S=1) result as the most
> stable configuration. I've published some results, obtained at a
> restricted open-shell level on the tetranuclear (something in the SI)
> and (mainly) on larger complexes here
> Mattioli et al.; J. Am. Chem. Soc. 2013, 135, 15353−15363
> The interesting thing (and still under investigation) is that in
> larger Co(III)-oxo clusters the peripheral Co atoms seem not to couple
> in a low-spin fashion with the other ones, when investigated at DFT+U
> level, as opposite to the B3LYP case. If you are interested I can send
> you some more details offline (after tuesday, however). A very similar
> tetranuclear Ni-oxo compound has been investigated here
> Cao et al.; PRL 100, 167206 (2008)
> And a very complex antiferromagnetically-coupled (or broken-symmetry,
> if you prefer) high-spin has been spotted by DFT+U(Ni,O), and
> confirmed by comparison of calculated and measured coupling constants J.
>
> This said, the world of open shell transition metal complexes is vast,
> and of course there is something that does not fit in my previous
> simple solution to Alex's problem. On the other hand, the fact that if
> you stretch an H2 molecule and use EXX you will obtain overcoupling of
> electrons is a matter of fact. Anyway, we may discuss again (after
> next tuesday...) the properties of further compounds.
>
> All the best
>
> Giuseppe
>
> Giuseppe Mattioli
> ISM-CNR
> Giuseppe
>
>
>
>
>
> Quoting Jia Chen <jiachenchem at gmail.com>:
>
> > Dear Giuseppe Mattioli,
> >
> > It is quite surprising for me, that hybrid functional actually
> > overestimates stability of low-spin solution. I know a compound ,for
> > which, hybrid functional overestimates stability of high-spin solution.
> Do
> > you know any published papers with examples of hybrid functional favours
> > low-spin? Thank you very much!
> >
> > Bests
> > Jia
> >
> >
> > On Fri, Jan 3, 2014 at 2:13 PM, Giuseppe Mattioli <
> > giuseppe.mattioli at ism.cnr.it> wrote:
> >
> >>
> >> Dear Alex
> >> Paolo is right, of course. Check the convergence on the Re PP first.
> >> I would add a few words anyway. Hybrid DFT/HF functionals like B3LYP
> >> are pretty useful, but in the case of open-shell systems there are
> >> some known limitations. See the very interesting paper by Cohen
> >> (Science Vol. 321 no. 5890 pp. 792-794). The HF exchange term added to
> >> the DFT xc kernel leads to an overcoupling of electron pairs and,
> >> therefore, to an overestimate of the stability of low-spin solutions.
> >> Chemists usually call it a "static correlation" error. As we could
> >> spend years in discussing such an issue, I feel to suggest two simple
> >> tests: try to perform a B2PLYP calculation (if you can afford it) with
> >> your GTO package. The MP2 treatment of B3LYP correlation is supposed
> >> to correct part of the static correlation error. Otherwise, try to
> >> perform a DFT+U calculation with the U correction applied (possibly in
> >> a self-consistent fashion, see the many related papers by Cococcioni,
> >> De Gironcoli, Kulik, Marzari, and mine) to the Re 5d shell (I did
> >> never use Re... Are the 4f electrons embedded in the pseudo?). The
> >> on-site DFT+U method is supposed to be free from sce, or, better, less
> >> affected than its parent DFT functional. If you obtain a high-spin
> >> solution with one of these methods, there are sound reasons, in my
> >> opinion, to trust that it is a stable solution...
> >> HTH
> >> Giuseppe
> >>
> >> Giuseppe Mattioli
> >> ISM-CNR
> >> Italy
> >>
> >> Quoting Alex Granov <alex.granov at outlook.com>:
> >>
> >> > Hi
> >> > We are studying an organo-metallic compound which contains 3 Benzene
> >> > rings, phosphorous, oxygen, Iodine, and rhenium atoms.Our quantum
> >> > chemistry study using B3LYP/6-31+G* (Gaussian basis set) shows that
> >> > the ground state of the system is singlet (spin -unpolarized). We
> >> > attempted to optimize this structure using quantum espresso to
> >> > calculate some other electronic properties. Then surprisingly we
> >> > found that the spin-polarized system is more stable than the
> >> > spin-unpolarized one in contrast with our quantum chemistry study.
> >> > In the following you can see my input file and I wonder whether
> >> > there is something wrong in the input that made the very noticeable
> >> > contrast. I appreciate your comments to understand the issue and
> >> > solve it in advance.
> >> > q/e input:&control calculation='relax',
> >> > restart_mode='from_scratch', prefix='Re-Be', pseudo_dir =
> >> > './pseudo/', outdir='./tmp/', tprnfor=.t. ,
> >> > etot_conv_thr=1.0D-4, forc_conv_thr=1.0D-3, nstep=300,
> >> > dt=10, / &system ibrav= 8, a=20, b=20, c=20, nat=37, ntyp=6,
> >> > ecutwfc = 30, ecutrho = 300, occupations='smearing',
> >> > smearing='marzari-vanderbilt', degauss=0.005, nspin=2 ,
> >> > starting_magnetization(1)=1 ,starting_magnetization(2)=1 ,
> >> > starting_magnetization(3)=1 , starting_magnetization(4)=1 ,
> >> > starting_magnetization(5)=1 , starting_magnetization(6)=1 , /
> >> > &electrons conv_thr = 1.0d-6, mixing_beta=0.2,
> >> > mixing_mode=local-TF, / &IONS ion_dynamics="bfgs", upscale=100.0D0
> >> > ,/ATOMIC_SPECIESRe 186.207 Re.pbe-hgh.UPFO 15.999
> >> > O.pbe-rrkjus.UPFC 12.000 C.pbe-rrkjus.UPFH 1.000
> >> > H.pbe-rrkjus.UPFI 126.90 I.pbe-n-rrkjus_psl.0.2.UPFP 30.9737
> >> > P.pbe-n-van.UPFK_POINTS {gamma}
> >> >
> >> > -------------------------------------------------Alex
> >> > GranovМосковский физико-технический институт (MIPT)Moscow, Russia
> >>
> >>
> >> --
> >> ********************************************************
> >> - Article premier - Les hommes naissent et demeurent
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> >> ne peuvent être fondèes que sur l'utilitè commune
> >> - Article 2 - Le but de toute association politique
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> >> ********************************************************
> >>
> >> Giuseppe Mattioli
> >> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> >> v. Salaria Km 29,300 - C.P. 10
> >> I 00015 - Monterotondo Stazione (RM)
> >> Tel + 39 06 90672836 - Fax +39 06 90672316
> >> E-mail: <giuseppe.mattioli at ism.cnr.it>
> >>
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> >
> >
> >
> > --
> > Jia Chen
>
>
> --
> ********************************************************
> - Article premier - Les hommes naissent et demeurent
> libres et ègaux en droits. Les distinctions sociales
> ne peuvent être fondèes que sur l'utilitè commune
> - Article 2 - Le but de toute association politique
> est la conservation des droits naturels et
> imprescriptibles de l'homme. Ces droits sont la libertè,
> la propriètè, la sùretè et la rèsistance à l'oppression.
> ********************************************************
>
> Giuseppe Mattioli
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> v. Salaria Km 29,300 - C.P. 10
> I 00015 - Monterotondo Stazione (RM)
> Tel + 39 06 90672836 - Fax +39 06 90672316
> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
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--
Jia Chen
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