[Pw_forum] Regarding controlled dynamics

[Marzari Nicola]

Not evident that fixing layers is good, btw - you are screening less.

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> On 22 May 2017, at 23:08, Matic Poberznik <matic.poberznik at gmail.com> wrote:
> 
> Dear Vipul,
> 
>> Hi all,
>> I am planing to work on interfaces. In doing so, I want to keep few layers
>> of a structure fixed while few to relax. In short this is what I am
>> planning :
> 
> 
> If I understood correctly and you're doing a relaxation the simplest way
> to fix atomic positions is to add 0 0 0 at the end of the specifed
> coordinate in the ATOMIC_POSITIONS card, (this will fix each component
> in x y y directions respectively) if you need to free up one direction
> replace the 0 by 1 i.e.
> 
> ATOMIC_POSITIONS
> A x y z 0 0 0
> 
> or to allow movement in one direction (x)
> 
> A x y z 1 0 0
> 
>> 10A vacuum
>> 2layers fixed
>> 4layers to relax
>> 2layers fixed
>> 
> 
> It's difficult to say without further information but make sure that the
> largest cell parameter (typically where you put the vacuum, is oriented
> in the z direction (due to parallelization)). I don't think esm and
> assume_isolated is needed in this case as long as your vacuum is large
> enough so that there is no interaction between the periodic slabs.
> 
> Hope this helps and best regards,
> 
> Matic
> -- 
> Matic Poberznik
> J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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