[Pw_forum] fix ions during relaxation / compile as a library?

[Lorenzo Paulatto]

On 04/04/2013 12:04 PM, Denis Davydov wrote:
> 1)
> I've been studying documentation, in
> particular of CP package, but could not find any way to fix
> positions of certain (some of all)
> ions during relaxation. In other words, exclude those from optimization.
> Is it currently possible?

yes, just add after the position of each ion three more columns 
(corrsponding to x,y and z) each column may contain a 1 (this coord of 
this atom can move) or a 0 (this coord of this atom does not move). 
Check the input manual for details

> 2) is it possible to compile QE as a library (preferably C++) and
> then provide an MPI communicator to be used, something like:
>
>     MPI_Comm_split(MPI_COMM_WORLD,my_color,0,&comm_qe);
>     qe   = new QE_NS::QE(0,NULL,comm_qe);
>     qe.run("my_input.txt");
No... not yet at least. It's not that easy to do. I know that some work 
in this direction has been done, and IS being done right now. i.e. PW 
can be used as a plugin for PLUMED (or PLUMED as a plugin for PW, 
depending on the website you're on); so maybe you can study and reuse 
this interface mecanism.

cheers
> Kind regards,
> Denis


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
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