[Pw_forum] warning in q2r.x

[Paolo Giannozzi]

Subhradip Ghosh wrote:

> "fft-check warning: sum of imaginary terms = .2454409E-06"
> 
> How serious is this warning and what could be the consequences? 

since the sum of imaginary terms is so small, I wouldn't mind too much

> Also, what could be the possible reasons?

numerical noise in the dynamical matrices, which could come
from inperfect convergence of the phonon calculation

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy