[Pw_forum] finding symmetry

[Paolo Giannozzi]

On Friday 23 May 2003 16:37, ma Yanming wrote:
> [...] this problem is from that the fractional translation
> is incompatible with the FFT grid.
> Is this behavior of finding less symmetries harmful to the calculation
> without concerning the calculating time?

no, it is not. The system must converge to the solution with the
good symmetry, whether it is imposed or not.

> How to solve it if I have to fix the unit cell and ecutwfc?

you can specify in input a slightly enlarged (or reduced, at your risk) 
FFT grid that is commensurate with the fractional translation

Paolo
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Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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