[Pw_forum] Convergence test, vc-relax calculation

[Anik Mondol]

Thanks a lot , Mr Ari
Regards
Anik

On Sun, Nov 26, 2017 at 7:33 PM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>
wrote:

>
> Dear Mondol Anik Kumar,
>
>  1) It depends on which quantities you mean hear: The ecutwfc (and
> ecutrho, if using Vanderbilt/USPP or PAW) are universal so long as you have
> not added or changed new pseudo potentials/PAW data sets; k points, one can
> in general estimate the spacing (in reci-procal space, naturally) from the
> bulk, unless the physics is radically different (for example one system
> metallic, the other one insulating)
>
>  2) You can use "restart_mode = 'restart'" and you do not have to update
> the geometry or cell in the input file; I tend to do this anyway, in case I
> once want to do a "restart_mode = 'from_scratch'"
>
>     Greetings from Paris,
>
>        apsi
>
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=
> -=*=-=*=-=*=-=*=-
>   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
>     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
>     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935
>
>
> On Sun, 26 Nov 2017, Anik Mondol wrote:
>
> Dear Users,I am new to quantum espresso. I appreciate the things that can
>> be done by quantum espresso. I have  some specific queries. I will get
>> to the points
>>
>> My intention is to calculate bandstructure of GaN nanowire. I have
>> carried convergence test ( ecutwfc, kpoint , lattice parameters( a,c)) for
>> GaN
>> supercell.
>> Then I constructed a nanowire supercell by adding vacuum . Then I have
>> performed a self-consistent and vc-relax calculation
>>
>> Now my confusion is this :
>>
>> 1. Did I need to carry out convergence test for the supercell as well ?
>>
>> 2.After the vc -relax calculation, I want to do a final scf calculation
>> do I need to update my input file with the optimized results  from the
>> outputs of vc-relaxation or QE reads data from the saved directory ?
>>
>> Regards
>>
>> Mondol Anik Kumar
>> Department of Electrical and Electronic Engineering
>> Bangladesh University of Engineering and Technology
>>
>
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