[Wien] Problem with geometry minimzation

[Peter Blaha]

w2web sets R0 automatically to a correct value.
And WIEN2k_10 complains during init_lapw if R0 is too big !

Am 02.11.2010 20:37, schrieb Saeed Bahramy:
> Dear Laurence,
>
> Thanks a lot. That was indeed the reason why I couldn't optimize the
> atomic positions. Reducing (!) R0 to 0.00001, I could successfully
> minimize all the forces. Now they're all well below 1.0 mRy/a.u..
>
> By the way, you said that my initial R0 was too small, but I had to
> further reduce it in order to get min_lapw working! Am I picking up
> wrong R0 for Te!? (UG says it should be between 0.0005 to 0.00005)
>
> Thanks again,
> Saeed Bahramy
>
>
> On Nov 3, 2010, at 3:08 AM, Laurence Marks wrote:
>
>> Te, R0 is too small.
>>
>> 2010/11/2 Saeed Bahramy <bahramy at riken.jp>:
>>>
>>> Ok. From this you can clearly see that E-tot and FGL does not fit
>>> together.
>>>
>>> Smaller forces give less negative E-tot. (At least if forces on other
>>> atoms
>>> do not destroy this simple logic) and since PORT minimizes E-tot, it
>>> finishes,
>>> although it has non-zero forces.
>>>
>>> Well, for those steps the total forces on other atoms are large and
>>> that's
>>> the reason why E-tot is less negative. For example in the second
>>> step, the
>>> total forces on all atoms are as follows:
>>> :FGL001: 1.ATOM 0.000000000 0.000000000
>>> -16.042000000 total forces
>>> :FGL002: 2.ATOM 0.000000000 0.000000000
>>> 41.642000000 total forces
>>> :FGL003: 3.ATOM 0.000000000 0.000000000
>>> 10.710000000 total forces
>>> and accordingly in this steps :ENE is the highest.
>>>
>>> I'm quite sure that my struct file is correct. The initail
>>> coordinates (as
>>> well as lattice parameters) have been taken from experiment. Before
>>> restarting the min_lapw calculation,
>>>
>>> This does not say anything. Is R0 ok ? RMTs set properly ?
>>>
>>> R0=0.0001 and RMT=2.5 (for all three atoms). Once again, there is no
>>> touching between the MT's
>>>
>>> I do remove histories (*broyd* and *tmpM files). Below, you can find the
>>> summary of (one of) my min_lapw calculation:
>>>
>>> Is it always like this, or other runs are different ?
>>>
>>> I always remove the histories before restarting min_lapw with a new
>>> case.inM
>>>
>>>
>>> If yes, the problem must be somewhere else and again, without testing
>>> myself,
>>> I cannot give more than the "standard hints", although the problem
>>> may stem
>>> from something completely different ( Are you using the latest WIEN2k
>>> version
>>> and have followed all bug-fixes discussed on the mailing list ?)
>>>
>>> My current version of WIEN2K is 10.
>>> Anyway, using this version of WIEN2K, I have been able to do geometry
>>> optimization for other systems without any problem.
>>>
>>> This almost always means that the user (you) has set the IDFT problem
>>>
>>> up incorrectly -- GIGO.
>>>
>>> Have you read the optimization notes at
>>>
>>> http://www.wien2k.at/reg_user/textbooks/ ? Do you have almost touching
>>>
>>> spheres, bad RKMAX, k-points etc?
>>>
>>> --
>>>
>>> P.Blaha
>>> --------------------------------------------------------------------------
>>>
>>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>>> Phone: +43-1-58801-15671 FAX: +43-1-58801-15698
>>> Email: blaha at theochem.tuwien.ac.at WWW:
>>> http://info.tuwien.ac.at/theochem/
>>> --------------------------------------------------------------------------
>>>
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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.
>> _______________________________________________
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>
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-- 
Peter Blaha
Inst.Materialchemie, TU Wien
Getreidemarkt 9
A-1060 Vienna
Austria