[Pw_forum] (no subject)

[shiva mokhavat]

Dear users
I have a question about the output of vc-relax. when I run vc-relax for
orthorhombic structure, the output celldms are so different from
experimental data. forexample celldm(1) is 8.896 bohr from experimental
data, but the output celldm(1) from vc-relax is 6.960 bohr.
my input file is:
&CONTROL
      calculation='vc-relax'
     restart_mode ='from_scratch',
           outdir = '/home/izadi/tmp/vc.orthorhombic',
           prefix = 'VC',
       pseudo_dir = '/home/izadi/pseudo/',
         tstress  = .TRUE.,
         tprnfor  = .TRUE.,
 /
 &SYSTEM
        ibrav = 9,
    celldm(1) = 8.896,
    celldm(2) = 1.051,
    celldm(3) = 0.998,
           nat= 8,
         ntyp = 2,
        nspin = 1,
      ecutwfc = 30,
      ecutrho = 120,
  occupations = 'smearing',
       degauss= 0.01,
&electrons
     conv_thr=1.D-5,
     mixing_beta=0.7,
 /



































                 &ELECTRONS
         conv_thr = 1.D-6,
      mixing_beta = 0.7,
/
 &IONS
  ion_dynamics = 'damp'
/
 &CELL
 cell_dynamics='damp-w'
 /
ATOMIC_SPECIES
 Ga    69.72   Ga.pz-bhs.UPF
  P     30.974  P.pz-bhs.UPF

ATOMIC_POSITIONS   (crystal)
 Ga     0.000     0.624    0.250
 Ga     0.000     0.376    0.750
 Ga     0.500     0.124    0.250
 Ga     0.500     0.876    07500
 P      0.000     0.152    0.250
 P      0.000     0.848    0.750
 P      0.500     0.652    0.250
 P      0.500     0.348    0.750
K_POINTS   (automatic)
4 3 5    0  0  0
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