[Wien] A basic question regarding structure optimization

[shamik chakrabarti]

Dear Prof. Blaha,

             Thank you for your reply. It will be helpful to us. I have
another question.

As you have told sometimes "the error could be very large (giving you
meaningless results)"

Does it mean that we may run into a local minima instead of global
minima...if the "error" is large?

looking forward to your response.

with regards,


On Mon, Sep 23, 2013 at 11:36 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.at>wrote:

> You CAN DO AND probably SHOULD ALWAYS DO a simultaneously optimization of
> external (lattice parameters) and internal (atomic positions) degrees of
> freedom with wien2k.
> Just use MSR1a  in the   run_lapw  step in volume optimization or replace
> run_lapw by min_lapw in any script.
>
> The "error" could be small (or almost zero), or could be very large
> (giving you meaningless results). This depends on your specific case.
>
>
>
> On 09/23/2013 06:27 AM, shamik chakrabarti wrote:
>
>> Sir,
>>
>>       I have a basic question regarding the method of structure
>> optimization in wien2k.
>>
>> If we optimize it in two  successive steps (i) first optimize volume and
>> lattice parameters and then (ii) for structure having optimized volume
>> and lattice parameters further optimization of structural
>> coordinates......
>>
>> how much different (or how much erroneous !!) will be the final optimize
>> structure in comparison to that obtained by simultaneous variation of
>> lattice parameters and structural coordinates as can be done in PAW code
>> VASP.
>>
>> Any response in this regards 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
>>
>>
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>>
>>
> --
>
>                                       P.Blaha
> ------------------------------**------------------------------**
> --------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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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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