[Wien] Fwd: not getting convergence with MBJ potential
Laurence Marks
L-marks at northwestern.edu
Mon Dec 12 14:22:38 CET 2011
I wonder whether you really have the structure right.
a) When you say that you get the same structure, what R-factor? Powder
diffraction is not very sensitive to oxygen positions in the presence
of heavy metal atoms.
b) If GGA takes about 80 iterations I suspect that you have a metal.
If you do not have the correct number of oxygen versus metal atoms you
will get this, and no amount of U or mBJ will change this (in 99% of
cases). Check the bond-valence sums of your model, are the numbers
reasonable? This is a standard test in solid-state chemistry.
c) Do you have large forces (as Peter asked)? If you do this also
indicates that you have the structure wrong.
d) When you say that you were using a greed of 0.2 (please do not use
the term "mixing factor", it is misleading) was this for Pratt or
MSR1? A change from 0.2 to 0.15 with MSR1 will not matter much.
2011/12/12 shamik chakrabarti <shamikphy at gmail.com>:
> Dear Dr Peter Blaha and Dr Pascal,
>
> The material is a ferrimagnetic transition
> metal compound and a charge transfer insulator and the gap is between d and
> O p states. Yes we have started MBJ potential calculation from the converged
> GGA charge density. So what we can do, we can start from the scratch with
> MBJ potential and after few iterations will get shifted to MSR1 mixing to
> improve the convergence. We hope that will help. Thank you for all your
> helps.
>
> with regards,
>
>
> On Mon, Dec 12, 2011 at 1:31 PM, pascal boulet
> <pascal.boulet at univ-provence.fr> wrote:
>>
>>
>> Dear Dr. Chakrabarti,
>>
>> All right. So, another idea: could it be that you restarted your m-BJ
>> calculation using the converged GGA or GGA+U density? I ran into these
>> kinds of troubles several times. I found it preferable to start from
>> scratch...
>>
>> Hope this help,
>> Pascal
>>
>> On 12/12/2011 08:45, shamik chakrabarti wrote:
>> > 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
>> > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>> >
>> > * Français - détecté
>> > * Anglais
>> > * Français
>> >
>> > * Anglais
>> > * Français
>> >
>> > <javascript:void(0);>
>> > _______________________________________________
>> > Wien mailing list
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>> > <mailto:Wien at zeus.theochem.tuwien.ac.at>
>> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> >
>> >
>> >
>> >
>> > --
>> > 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
>> > 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
>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
>
>
>
> --
> 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
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
--
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi
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