[Pw_forum] IFC file convention clarification

[Paolo Giannozzi]

On Tue, 2014-11-04 at 23:12 -0800, Navaneetha Krishnan wrote:

> I am trying to calculate the IFCs for a FCC lattice (Al) for a few
> nearest neighbours. I was following a set of threads, which led me to
> this one :
> 
> http://www.democritos.it/pipermail/pw_forum/2009-August/013613.html

> Could someone elaborate on the statement (in this webpage),
> "Notice also that the force constant grid is written as these were  
> periodic ...
> so in a 4x4x4 grid R(1,1,1) = 0,  R(2,1,1,) = a1,  and  R(4,1,1)=-a1"?
> 
> More specifically, what is R(3, 1, 1) in this case? 

2*a1

Paolo

> Thanks a lot!
> --
> Navaneeth
> Caltech
> 
> 
> 
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222