[Pw_forum] about phonon calculation

[Paolo Giannozzi]

On Tuesday 11 July 2006 10:59, Ezad Shojaee wrote:

> i have made a phonon calculation with a small grid (221)  [...]
> when i  want to calculate the IFC's in the real space with q2r.x ,
> there is no dielectric tensor 

this is normal, if you do not explicitly require its calculation
by ph.x (epsil=.true.)

> & i have this error too : 

>    from init : error #         1
>      q not allowed

there is a mismatch between what the q2r.x code thinks 
q-points should be, and what you provided. It is sufficient
that a coordinate differs by 10^-5 from what it should be
to get this error. Please check what you used as q-points

Paolo
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