[Pw_forum] on nosym=.true.

[Gabriele Sclauzero]

Il giorno 24/nov/2010, alle ore 10.39, Mahmoud Payami ha scritto:

> Dear QE experts,
> I am doing slab calculations, and have let the interlayer spacings change 
> along z-direction. I sometimes encounter the message: "the symmetry 
> opetarion  #... is not...", and sometimes this problem causes the program 

Do you mean "Warning: symmetry operation #N not allowed"? This is not an error, but simply a warning, please have a look here:

http://www.quantum-espresso.org/user_guide/node50.html#SECTION0001110200000000000000

I doubt that this would cause the program to stop.

> stop. However, I followed Eyvaz's suggestion in the forum and added 
> "nosym=.true." in &SYSTEM. Now there is no complain about symmetry operation 
> but the number of k-points has been increased.

Of course, they cannot be reduced by symmetry since you asked the code to ignore any symmetry operation that might be present.

> My question is: using 
> "nosym=.true.", what symmetry operations are ignored, and where should I 

All.

> refer to find out which symmetry operation number refers to what?

use verbosity = 'high' in namelist &control or look into the source code.

HTH

GS

> Best regards,
> Mahmoud Payami,
> 
> Physics Group, AEOI, Tehran, Iran. 
> 
> 
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§ Gabriele Sclauzero, EPFL SB ITP CSEA
   PH H2 462, Station 3, CH-1015 Lausanne

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