[Wien] Fwd: not getting convergence with MBJ potential
Peter Blaha
pblaha at theochem.tuwien.ac.at
Mon Dec 12 09:00:09 CET 2011
When you need 80 iterations with GGA, it is rather clear that also mBJ will take a long time
(usually a bit longer ....).
Anyway: Have you checked the forces (total, not partial !!) in the GGA calculation. Small forces
will tell you that your structure is probably ok, large forces (gt. 10-20) means that the structure is
NOT ok.
The "TAUWRONG" messages indicate, that the kinetic energy density is not accurate (we check some
known constrains like positive tau, comparison with tau-weizäcker,...., and limit wrong values.
Something like this may happen at the beginning of mBJ, but usually indicate that the calculations are
not well converged (RKmax, GMAX ?) or the vresp file and the clmsum file do not match properly.
PRATT with 0.15 at the beginning should be fine. Usually, after 10-20 iterations one should see
"grep :DIS case.scf" starting to decrease slightly but steadily. At this stage one can usually
switch to MSR1 to accelerate convergence.
BUT: If this is a transition metal compound and the gap is expected between partially occupied d-bands,
but LDA+U does not give a gap, then I also expect that something is wrong with the (magnetic ??) structure ...
E.g.: a ferromagnetic solution will stay magnetic, while a PROPER AFM structure may give an insulator.....
Am 12.12.2011 08:45, schrieb shamik chakrabarti:
> Dear Dr. Pascal,
>
> As we were getting Ghost band error due to large charge fluctuation during initial cycle *we have reduced the mixing parameter from 0.2 to 0.15 & hence thereafter
> we have not received ghost band error yet.*
>
> As long as variation of RMT is concerned the variation is only from 1.7 to 2.01 in the structure.
>
> So far there is no energy equivalence between a local orbital and overall energy parameter which can induce ghost band error.
>
> Also we have achieved convergence of -0.000034 with plain GGA and only with MBJ potential we are getting the convergence problem and again plain GGA and also GGA+U have not given
> the proper electronic structure.
>
> As far as the structure is concerned we are very much sure about its structural parameters as they are giving the same XRD as experiment when the positional coordinates and
> lattice parameters of the 56 atom cell were put into a software powdcell.
>
> looking forwards to your comments.
>
> with regards,
> On Mon, Dec 12, 2011 at 12:26 PM, pascal boulet <pascal.boulet at univ-provence.fr <mailto:pascal.boulet at univ-provence.fr>> wrote:
>
> Hello,
>
> It is strange that you have such a bad convergence on the energy and the
> charge after that many cycles.
> My feeling is that something is wrong in the input.
>
> Have a look at the user manual. From page 205 on, there is an
> explanation of the meaning of ghost bands. You have to experiment on
> your chemical system to get rid of them.
>
> Pascal
>
>
> On 12/12/2011 05:21, shamik chakrabarti wrote:
> > Dear wien2k users,
> >
> > Any response of my previous mail will be very
> > helpful for us. Eagerly waiting for your comments.
> >
> > with regards,
> >
> > ---------- Forwarded message ----------
> > From: *shamik chakrabarti* <shamikphy at gmail.com <mailto:shamikphy at gmail.com>
> > <mailto:shamikphy at gmail.com <mailto:shamikphy at gmail.com>>>
> > Date: Sun, Dec 11, 2011 at 5:42 PM
> > Subject: not getting convergence with MBJ potential
> > To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at <mailto:wien at zeus.theochem.tuwien.ac.at>
> > <mailto:wien at zeus.theochem.tuwien.ac.at <mailto:wien at zeus.theochem.tuwien.ac.at>>>
> >
> >
> > Dear wien2k users,
> >
> > I am trying to simulate electronic structure of
> > a charge transfer insulator. Our system consists of a unit cell having
> > 56 atoms and we are using 14 k-points. As GGA+U method was failed to
> > reproduce the proper band gap (in fact much less than the
> > experimentally obtained one) we have opted for MBJ potential.
> > *Initially the mixing parameter was set to 0.2 and we got Ghost band
> > error after few iterations. Hence we reduce the mixing parameter to
> > 0.15.* Until now still it has shown no error except some extra message
> > in case.dayfile. I am giving those messages below. So far e.c. & c.c
> > were achieved up to 2.239... & 5.4599 respectively and already 36
> > iterations are over. My questions are:
> >
> > (1) Is it ok to set up a mixing parameter of 0.15 that is with it, is
> > it possible to reach convergence?
> >
> > (2) As plain GGA takes around 80 iterations to converge, is it that
> > MBJ potential will take much higher than that as we know it is always
> > hard to get convergence with this method?
> >
> > (3) what are the meanings of the given messages below:
> >
> > lapw2 -c -up -vresp (17:12:13) > lapw1 -c -dn (16:19:33)
> > 10848.369u 98.026s 52:39.78 346.4%0+0k 0+1099920io 0pf+0w
> > > lapw1 -c -up (15:26:49) 10864.462u 99.082s 52:44.39 346.4%0+0k
> > 0+1100232io 0pf+0w
> > 460.324u 151.313s 6:52.62 148.2%0+0k 0+732368io 0pf+0w
> > -5.956509016536202E-002
> > 3.325214690385789E-002 -9.166205529297161E-002 tauwrong=
> > int:rho,tauw,grho,g2rho 2.146196813781874E-002 1.287982148952303E-002
> > -4.564940741427861E-002
> > 3.061850458947012E-002 -5.357427363703868E-002 tauwrong=
> > int:rho,tauw,grho,g2rho 1.778719641126464E-002
> > 1.317651193616000E-002 *what is tauwrong?*
> > -4.561631481999567E-002
> > 3.051935798833875E-002 -5.372842413400847E-002 tauwrong=
> > int:rho,tauw,grho,g2rho 1.783702549056333E-002 1.305474408433668E-002
> > -2.872847342414767E-002
> > 2.625149916992486E-002 -2.271097056901070E-002 tauwrong=
> > int:rho,tauw,grho,g2rho 1.456340274765583E-002 1.183001700580401E-002
> > -2.843529510619935E-002
> > 2.607602777746414E-002 -2.279192386903682E-002 tauwrong=
> > int:rho,tauw,grho,g2rho 1.462794826548238E-002 1.162089194449066E-002
> > -1.211083415464120E-002
> > ..........................................
> > ..........................................
> > > lapw0 (15:19:56) sphere:rho,tauw,grho,g2rho 7.46875999972237
> > 180.956718336004
> > > lapw0 -grr (15:15:10) 315.375u 93.253s 4:45.73 143.0%0+0k
> > 0+................
> >
> >
> > Any response in this regard will be very helpful for us. Thanks in
> > advance.
> >
> > with regards,
> > --
> > Shamik Chakrabarti
> > Senior Research Fellow
> > Dept. of Physics & Meteorology
> > Material Processing & Solid State Ionics Lab
> > IIT Kharagpur
> > Kharagpur 721302
> > INDIA
> >
> >
> >
> > --
> > Shamik Chakrabarti
> > Senior Research Fellow
> > Dept. of Physics & Meteorology
> > Material Processing & Solid State Ionics Lab
> > IIT Kharagpur
> > Kharagpur 721302
> > INDIA
> >
> >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at>
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
> --
> Dr. pascal Boulet, computational chemist
> University of Aix-Marseille I
> Laboratoire Chimie Provence, UMR 6264
> Group of Theoretical Chemistry
> Avenue Normandie-Niemen
> 13397 Marseille Cedex 20
> France
> **********
> Tel. (+33) (0)413.55.18.10
> Fax. (+33) (0)413.55.18.50
> **********
> http://www.lc-provence.fr
> https://sites.google.com/a/univ-provence.fr/pb-comput-chem
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>
>
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
>
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> Wien at zeus.theochem.tuwien.ac.at
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--
P.Blaha
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