[Pw_forum] Fractional translations in magnetic system

MKondrin mkondrin at hppi.troitsk.ru
Sun Feb 22 11:57:18 CET 2015

Dear QE users and developers!

I want to calculate properties of FeS2 (pyrite), space group Pa-3. 
First, I use non-relativistic pseudopotentials

Fe 55.845 Fe.pw-mt_fhi.UPF
S 32.066 S.pw-mt_fhi.UPF

and to make QE properly find all (24) symmetry operations I had to set 
parameters nr1=100,nr2=100,nr3=100. In this case this trick works.

However when I try to use relativistic pseudopotentials

Fe 55.845  Fe.rel-pbe-spn-kjpaw_psl.0.2.1.UPF
S 32.066 S.rel-pbe-n-kjpaw_psl.0.1.UPF

with the spin-orbital interaction ( lspinorb=.true., 
starting_magnetization=0.5, noncolin=.true., however the system should 
be diamagnetic) I always get in the output file the message

 8 Sym. Ops., with inversion, found (18 have fractional translation)

If nr* parameters weren't set in input file, then the  automatically 
generated  FFT grid seems quite compatible with fractional translations:

 Dense  grid:   263859 G-vectors     FFT dimensions: (  80,  80,  80)

 Smooth grid:    84247 G-vectors     FFT dimensions: (  60,  60,  60)

Also setting nr1=100,nr2=100,nr3=100 (that is to the same values as in 
the non-relativistic case) didn't produce any effect. The program didn't 
find missing symmetry operations.

I am in a loss. Thank you for your help in advance (input file is 
attached to the mail).

Best regards,

M. V. Kondrin (High Pressure Physics Institute RAS, Troitsk, Russia)
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