[Pw_forum] Possible small Bug in ph.x?

[Miguel Martínez Canales]

Hello everybody,

I was doing some phonon runs in espresso 3.0. I was doing the run with 
ldisp=.true. and found the following (a 666 grid for a fcc):

$ cat ge.dyn0
...
    0.333333333333333E+00   0.277555756156289E-16   0.333333333333333E+00
....
    0.666666666666667E+00  -0.555111512312578E-16   0.666666666666667E+00
....

Well, I'm not that worried, as these deviations are very small from 0. 
However, I'm suspecting these two q points won't use full symmetry as if 
q(2)=0. Furthermore, the kpoints.x binary generated nice q points (zero was 
exactly zero).

Any comments on this?

The machine I run this into was a Itanium2 CPU. Espresso version 3.0 (not 
cvs). Both CC and FC were Intel v8. MKL8 was also used. No fancy compiler 
flags, only -O2 -tpp2 (Itanium2 optimizer) and -mcpu=itanium2 for icc.

I just tried this on a P4 2.6, compiled with g95 and SSE2 optimized atlas. 
And the same numbers appear. So I shouldn't worry, should I?

Thank you for your comments,

Miguel

-- 
----------------------------------------
Miguel Martínez Canales
    Dto. Física de la Materia Condensada
    UPV/EHU
    Facultad de Ciencia y Tecnología
    Apdo. 644
    48080 Bilbao (Spain)
Fax:  +34 94 601 3500
Tlf:  +34 94 601 5437
----------------------------------------

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