[Pw_forum] Apparition of a non-90° angle in a QE optimisation

[hqtst42]

Dear all,

Doing a "vc-relax" optimisation using the file enclosed, (monoclinic
with β as unique angle) I find that another non-90° appears. This is
before the optimisation:

—————————————————————————————————————
  lattice    14.397000    0.000000    0.000000    0.000000   
7.818000    0.000000   -1.770149    0.000000  
10.355801—————————————————————————————————————

This is after the optimisation:

—————————————————————————————————————
  lattice    14.463802    0.000000    0.012905    0.000000   
7.596068    0.000000   -1.720133    0.000000  
10.061491—————————————————————————————————————

I know there is the parameter called "cell_dofree", but it only allows
you to either allow all angle and axis to be changed ('all') or only
axis ('xyz') but not just axis and the unique angle. I use QE v.6.1v .

Many thanks in advance for your help,

Henri

-------------- next part --------------
&control
   calculation = 'vc-relax',
   restart_mode = 'from_scratch',
   prefix = 'testmol',
   verbosity = 'default' ,
   tstress = .true.,
   tprnfor = .true.,
   pseudo_dir = '/home2/colaux/PPfiles/',
   outdir = '/tmp/exec-for-all/',
   etot_conv_thr = 0.0001 ,
   nstep = 100,
/

&system
   ibrav = -12
   space_group = 14
   uniqueb = .true.
   use_all_frac = .true.
   A = 13.397,
   B = 6.818,
   C = 9.506,
   cosAB = 0,
   cosAC = -0.16848937957,
   cosBC = 0,
   nat = 33
   ntyp = 3
   ecutwfc =50.0
   spline_ps = .true.
   tot_charge = 0
   /
&electrons
   electron_maxstep = 100,
   conv_thr = 1.0D-6 ,
   startingpot = 'atomic' ,
   startingwfc = 'atomic' ,
   mixing_mode = 'plain' ,
   mixing_beta = 0.7D0 ,
   mixing_ndim = 8,
   diagonalization = 'david' ,
   scf_must_converge = .FALSE. ,
   /
&ions
   ion_dynamics = 'bfgs'
/
&cell
    cell_factor = 2.0
/
ATOMIC_SPECIES
C 12.010  C.pbe-tm-new-gipaw-dc.UPF
H  1.007  H.pbe-tm-new-gipaw-dc.UPF
O 15.999  O.pbe-tm-new-gipaw-dc.UPF

ATOMIC_POSITIONS (crystal_sg)
C 0.41617 0.3483 0.3962  0 0 0
C 0.35013 0.2207 0.3217  0 0 0
C 0.3996 0.1089 0.2383   0 0 0
C 0.30378 0.1238 0.4203  0 0 0
C 0.21726 0.1726 0.4466  0 0 0
C 0.17604 0.0902 0.5385  0 0 0
C 0.22027 -0.0484 0.6065 0 0 0
C 0.30785 -0.0965 0.5821 0 0 0
C 0.34864 -0.0127 0.4879 0 0 0
C 0.17414 -0.1385 0.7045 0 0 0
C 0.09696 -0.2639 0.6467 0 0 0
C 0.0414 -0.3210 0.7486  0 0 0
C 0.1373 -0.4152 0.5836  0 0 0
H 0.4247 0.5665 0.4693   0 0 0
H 0.2948 0.2919 0.2600   0 0 0
H 0.4571 0.0403 0.2956   0 0 0
H 0.4299 0.1810 0.1712   0 0 0
H 0.3514 0.0176 0.1875   0 0 0
H 0.1812 0.2830 0.3945   0 0 0
H 0.1097 0.1262 0.5560   0 0 0
H 0.3458 -0.1972 0.6359  0 0 0
H 0.4175 -0.0544 0.4738  0 0 0
H 0.2270 -0.2108 0.7714  0 0 0
H 0.1455 -0.0431 0.7647  0 0 0
H 0.0510 -0.1936 0.5721  0 0 0
H 0.0865 -0.3837 0.8247  0 0 0
H 0.0101 -0.2159 0.7895  0 0 0
H -0.0163 -0.4031 0.7025 0 0 0
H 0.1799 -0.3750 0.5153  0 0 0
H 0.0799 -0.4965 0.5345  0 0 0
H 0.1806 -0.4871 0.6535  0 0 0
O 0.37920 0.4968 0.4148  0 0 0
O 0.49690 0.3117 0.4375  0 0 0
K_POINTS automatic 
1 1 1 1 1 1