[Wien] A basic question regarding structure optimization

[shamik chakrabarti]

Dear Prof. Blaha,

                      Thank you for your response. It clarifies our doubts.

with regards,


On Mon, Sep 23, 2013 at 3:10 PM, Peter Blaha
<pblaha at theochem.tuwien.ac.at>wrote:

> It means that the calculated value for the lattice parameters is (more or
> less) wrong.
>
>  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 <mailto:pblaha at theochem.**tuwien.ac.at<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
>>     Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
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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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>>
> --
>
>                                       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/**
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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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