[Wien] force optimization with MSR1a

[shamik chakrabarti]

Dera Prof. Blaha Sir,

                Thank you very much for your reply. It is indeed very
helpful. Yes energy convergence has been reached up to ~ 0.001 so far. Also
E-tot & FR is decreasing. We are using 14 k-points for a 56 atomic cell.
However, there is one doubt...the material is found to be in semiconducting
range with a band gap of ~3 eV. Do you think for such a high band-gap
material 80 iterations may not be much &  should we wait?

Thanks in advance.

with regards,


On Thu, Aug 28, 2014 at 3:22 PM, Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:

> 80 iterations for a more complicated MSR1a optimization is NOT much. I
> often need a couple of 100 iterations for a big (metallic and magnetic)
> system with 3d elements.
>
> However, make sure:
>
> grep :DIS case.scf is showing a "reasonable" convergence" (eg. it should
> not stay long above 1.0)
> grep :ENE case.scf   shows a trend that E-tot is reducing (not necessarily
> monotonically, but overall .
> grep :FR case.scf   is decreasing (overall).
>
> If these criteria are fulfilled, continue.
>
> If not, you may have started very poorly ?? or you should use a better
> k-mesh or TEMP+smearing, or your RMT,... is bad ....
>
>
>
> On 08/28/2014 10:46 AM, shamik chakrabarti wrote:
>
>>
>> Dear wien2k users,
>>
>>                         We are doing force minimization of a spinel
>> compound using MSR1a. After even 80 iterations, force on some atoms are
>> 200 mRy/a.u. while on some atoms it is ~ 7 mRy/a.u. We are using a
>> mixing grid of default 0.2 in case.inm.
>>
>> My query is that should we change this grid to say at 0.5 for speeding
>> up the process or will that change eventually sets some undesirable
>> oscillations in the calculation?....or should we just wait with all
>> default values as long as the force will not come below 5
>> mRy/a.u.?....or is their any prescription for optimizing the process to
>> get correct output in real time scale?
>>
>> 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
>>
>>
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>>
> --
>
>                                       P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/
> theochem/
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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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