[Pw_forum] for q2r.x errors

ma Yanming yanming_ma at hotmail.com
Thu Aug 28 20:57:58 CEST 2003


Dear Claudia,


>How did you define your unit cell in the input for the pw.x runs?
>
>If you used ibrav=0
>and then specified the lattice vectors using:
>CELL_PARAMETERS { cubic | hexagonal }
>     a(1,1) a(2,1) a(3,1)
>     a(1,2) a(2,2) a(3,2)
>     a(1,3) a(2,3) a(3,3)
>
>I am afraid this is the source of your problem running q2r.x
>
>The q2r program, as it is now written, reads in input dynamical
>matrices generated using ibrav=/=0 and uses the corresponding
>"automatic" choice for the lattice vector (generated by latgen).

I did not input in this way as you stated. I check the reference and find 
that for Alpha_Ga structure, the spacegroup is Cmca and Gallium atoms are 
in the 8f Wyckoff position, and y=0.1549 and z=0.081. So I set ibrav=9. The 
following is my input file for PW.x run. 

cat >Ga.scf.in <<EOF
Alpha_Ga
bco
&CONTROL
  calculation='scf',
  restart_mode='restart',
  tstress=.t.,tprnfor=.t.,
  PSEUDO_DIR='$PSEUDO_DIR/',
  outdir='$TMP_DIR/',
 /
&system    
    ibrav=  9, celldm(1) =8.42,celldm(2)=1.69468,celldm(3)=1.00168, 
    nat=  4, ntyp= 1,
    ecutwfc =60.0,nosym=.t.,
    occupations='smearing', smearing='methfessel-paxton', degauss=0.05
 /
&ELECTRONS
   conv_thr=1e-8,
   mixing_beta=0.7
/
ATOMIC_SPECIES
Ga 69.723 PS_Ga.af
ATOMIC_POSITIONS {crystal}
Ga  0.8451  0.1549  0.0810
Ga  0.6549  0.3451  0.5810
Ga  0.3451  0.6549  0.4190
Ga  0.1549  0.8451  0.9190
K_POINTS {automatic}
 8 8 8 0 0 0
EOF

I am just wondering how one can be confident with one's input.This is 
extremely important. 
Unfortunetaly, PWSCF doesn't perform the checking function. The only thing 
we can do is trying to analyze using the output symmetry operation. In my 
case, I did find 8 symmetry operation. But I am still not sure if my input 
is correct.

Yanming

>best regards,
>Claudia
>
>__________________________________________________
>Dr. Claudia Bungaro
>Dept. of Physics and Astronomy, Rutgers University
>136 Frelinghuysen Road, Piscataway,  NJ 08854-8019
>
>tel: +1 732 445 4197          fax: +1 732 445 4343
>email: bungaro at physics.rutgers.edu
>__________________________________________________
>
>
>On Thu, 28 Aug 2003, ma Yanming wrote:
>
> > Dear All,
> >
> > When I tried to calculate the force constant in Real space using q2r.x, 
I
> > met the following error message:
> >
> > reading dyn.mat. from file Case_3.dyn
> >  nqs=            2
> >  q=   0.00000000  0.00000000  0.82109896
> >  q=   0.00000000  0.00000000 -0.82109896
> >    1   1   2
> >
> > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> > from init : error #         1
> > nc already filled
> > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> >      stopping ...
> >
> > I know if one chooses the  wrong q points set to calculate the force
> > constant, then PWSCF will find the duplications.The error message will
> > occur as above. But I am confident that mine is not this case.
> >
> > My question is If my input atomic positions are wrong,will this error
> > message occur?
> > I still doubt about the input atomic coordinate for C-based 
Orthorhombic
> > unit cell as my previous email. But for that email, nobody reply me.
> > Does anyone have the successful experiences in calculating the phonon 
in
> > C_based orthorhombic unit cell?
> >
> > Any Comment?
> >
> > Thanks in advance.
> >
> > Yanming Ma PhD
> > Steacie Institute for Molecular Sciences,
> > National Research Councils of Canada.
> > 100 Sussex
> > K1A 0R6
> >
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> >
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> >
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