[Wien] Slab convergence

[Laurence Marks]

Pay attention to the warning about R0 and change this in the struct
file. (Previously it was possible to run calculations with too large a
value and not know.) Apart from this it is hard to know and rerunning
siteconfig is safer.

On Mon, Sep 13, 2010 at 7:36 AM, Lukasz Plucinski
<pluto at physics.ucdavis.edu> wrote:
>  Hello,
>
> I copied newest version of Wien2k (previously I was using version 08). I
> would really prefer to avoid compiling a new version, thus I just copied
> (overwritten) the binaries (executables) into the root Wien directory.
> However, not everything seems to work now...
>
> First I tried to calculate bulk Au as a test. Automatic RMT procedure has
> determined the RMT as 2.5 although it should be around 2.72... I don't
> understand why but this does not really change much.
>
> First warning appears when running lstart:
>
> WARNING: R0 for atom    1 Z= 79.00 too big
>
> There is no problems with leaking charge:
>
>  TOTAL CORE-CHARGE:                   54.000001
>  TOTAL CORE-CHARGE INSIDE SPHERE:     53.999826
>  TOTAL CORE-CHARGE OUTSIDE SPHERE:     0.000175
>
> Then the rest of initialization goes fine and there is no problem with
> convergence. I can also calculate the band structure, however, not the
> option of partial charges. Trying to calculate partial charges gives the
> following error:
>
>   Commandline: x lapw2 -band -qtl -up
>   Program input is: ""
> forrtl: severe (256): unformatted I/O to unit open for formatted transfers,
> uni
> t 15, file /local/WORK/Au-bulk-no-SO/Au-bulk-no-SO.tmpup
> Image              PC        Routine            Line        Source
> lapw2              082CDBED  Unknown               Unknown  Unknown
> lapw2              082CD165  Unknown               Unknown  Unknown
> lapw2              08288C98  Unknown               Unknown  Unknown
> lapw2              08252AFA  Unknown               Unknown  Unknown
> lapw2              0825241B  Unknown               Unknown  Unknown
> lapw2              08279804  Unknown               Unknown  Unknown
> lapw2              080899EE  outp_                     207  outp.f
> lapw2              0807B3AF  l2main_                  1710  l2main_tmp_.F
> lapw2              08083AFB  MAIN__                    545  lapw2_tmp_.F
> lapw2              080482A1  Unknown               Unknown  Unknown
> lapw2              082D8E30  Unknown               Unknown  Unknown
> lapw2              08048161  Unknown               Unknown  Unknown
> 0.324u 0.097s 0:00.42 97.6%     0+0k 0+2224io 0pf+0w
>
> Doing all this on my Fe1Au20 slab gives the same "WARNING: R0 for atom    1
> Z= 79.00 too big" warning, and then during SCF run the programs gets stuck
> on a first LAPW2, it does not give the error, but the LAPW2 continues
> forever... Thus probably there is something wrong with my LAPW2, or perhaps
> my Wien2k_10 is not properly installed.
>
> I will keep working to solve this, but I am sure your suggestions will help.
>
> Regards,
> Lukasz
>
>
>
> On 9/12/2010 3:37 PM, Laurence Marks wrote:
>>
>> N.B., of course when you compare to the number of k-points for bulk Au
>> remember to use the primitive cell volume.
>>
>> On Sun, Sep 12, 2010 at 8:21 AM, Laurence Marks
>> <L-marks at northwestern.edu>  wrote:
>>>
>>> Some comments:
>>>
>>> 1. 100 k-points for a surface is a lot. What I suggest you do is
>>> determine how many k-points you need per reciprocal nm^3 (i.e. the
>>> multiple of the 3 numbers after "div:" in line 1 of case.klist and the
>>> cell volume) for a bulk calculation then use the same density for a
>>> surface.
>>>
>>> 2. Are you using TETRA? I recommend TEMPS for surfaces with a
>>> temperature factor of 0.0018 (room temperature).
>>>
>>> 3. DO NOT REDUCE THE MIXING FACTOR (better called MIXING GREED) unless
>>> you understand what you are doing. For old PRATT and BROYD methods
>>> this was correct, for MSEC1 it is fundamentally wrong. Too large a
>>> mixing greed (say 0.5) is being too greedy, but the algorithm in fact
>>> prevents this from happening. To small a greed and the algorithm will
>>> starve to death.
>>>
>>> 4. In 98% of cases where the calculation does not converge this is
>>> because something is wrong in the physics of the model, i.e. bad
>>> functional or incorrect structure. Possibly the Fe atom is too far
>>> from the surface -- have you set FOR in case.in2 and looked at how big
>>> these are? With care, you can run a minimization with something like
>>> -fc 4 -ec 0.001 at first, then improve these later.
>>>
>>> 5. When you say it is not converging what do you really mean? The
>>> default -ec 0.0001 is very strict for a surface (with incorrect
>>> positions), realise that the energy convergence should scale as
>>> something like the number of atoms (or the square root of this).
>>>
>>> 6. Are you using 10.1 and iterative mode? 10.1 is noticeably better
>>> and I prefer to use -noHinv.
>>>
>>> On Sun, Sep 12, 2010 at 7:26 AM, Lukasz Plucinski
>>> <pluto at physics.ucdavis.edu>  wrote:
>>>>
>>>>  Hello,
>>>>
>>>> I am trying to calculate 1ML of Fe on top of Au(001).
>>>>
>>>> It was no problem to calculate 20ML slab of Au(001), it converged after
>>>> 37
>>>> iterations with mixing 0.1, 100k-points and all other standard settings,
>>>> also using "spin-polarized" calculation mode. I use 50 A of the unit
>>>> cell
>>>> dimension, to have appropriate amount of vacuum.
>>>>
>>>> However, when I put 1 Fe atom on top of one side of the slab the
>>>> calculation
>>>> didn't converge after 100 iterations (I did couple of trials). I also
>>>> tried
>>>> to increase the cutoff to -8 Ry, and the calculation is running now,
>>>> however, no convergence indications after 35 iterations.
>>>>
>>>> My slab is not relaxed, and the distance between Fe and Au (3.295 au) is
>>>> taken from the old publication of  Freeman JMMM 75, 201 (1988).
>>>>
>>>> Automatic RMT distance procedure has put all RTM to 2.5, however, this
>>>> way
>>>> there is a lot of space between Au atoms. I think its better to use 2.72
>>>> for
>>>> Au atoms and 2.34 for Fe atom -- is there any problem with this ?
>>>> Neither
>>>> setting helps the convergence...
>>>>
>>>> Maybe I could decrease the amount of k-points to have faster iterations
>>>> with
>>>> even lower mixing parameter ?
>>>>
>>>> Regards,
>>>> Lukasz
>>>> _______________________________________________
>>>> Wien mailing list
>>>> Wien at zeus.theochem.tuwien.ac.at
>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>>
>>>
>>>
>>> --
>>> Laurence Marks
>>> Department of Materials Science and Engineering
>>> MSE Rm 2036 Cook Hall
>>> 2220 N Campus Drive
>>> Northwestern University
>>> Evanston, IL 60208, USA
>>> Tel: (847) 491-3996 Fax: (847) 491-7820
>>> email: L-marks at northwestern dot edu
>>> Web: www.numis.northwestern.edu
>>> Chair, Commission on Electron Crystallography of IUCR
>>> www.numis.northwestern.edu/
>>> Electron crystallography is the branch of science that uses electron
>>> scattering and imaging to study the structure of matter.
>>>
>>
>>
>
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>



-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.