[Pw_forum] vc-relax

[Ganapati Natarajan]

Dear users,

I am trying to use the vc-relax option to optimise the
cell parameters for silicon. But in the output file
there are no updated cell parameters or atomic
positions. Please explain how to get these.

Thanks,

Gana


My input file is:

 &control
    calculation = 'vc-relax'
    restart_mode ='from_scratch',
    prefix='silicon',
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = '...'
    outdir= '...'
 /
 &system
    ibrav=  2, celldm(1) =15.20, nat=  2, ntyp= 1,
    ecutwfc =18.0,
 /
 &electrons
    mixing_mode = 'plain'
    mixing_beta = 0.7
    conv_thr =  1.0d-8
 /
&ions
ion_dynamics='damp'
/
&cell
cell_dynamics='damp-pr'
wmass=1.0
press=0.001
/
ATOMIC_SPECIES
 Si  28.086  Si.vbc.UPF
ATOMIC_POSITIONS crystal
 Si 0.00 0.00 0.00
 Si 0.25 0.25 0.25
K_POINTS
  10
 0.1250000  0.1250000  0.1250000   1.00
   0.1250000  0.1250000  0.3750000   3.00
   0.1250000  0.1250000  0.6250000   3.00
   0.1250000  0.1250000  0.8750000   3.00
   0.1250000  0.3750000  0.3750000   3.00
   0.1250000  0.3750000  0.6250000   6.00
   0.1250000  0.3750000  0.8750000   6.00
   0.1250000  0.6250000  0.6250000   3.00
   0.3750000  0.3750000  0.3750000   1.00
   0.3750000  0.3750000  0.6250000   3.00



A sample of my output is as follows:


!    total energy              =   -15.84452726 ryd
     estimated scf accuracy    <        2.6E-11 ryd

     convergence has been achieved

     Forces acting on atoms (Ry/au):

     atom   1 type  1   force =     0.00000000   
0.00000000    0.00000000
     atom   2 type  1   force =     0.00000000   
0.00000000    0.00000000

     Total force =     0.000000     
Total SCF correction =     0.000000


 entering subroutine stress ...

          total   stress  (ryd/bohr**3)               
  (kbar)     P=
-10.24
  -0.00006964   0.00000000   0.00000000        -10.24 
    0.00      0.00
   0.00000000  -0.00006964   0.00000000          0.00 
  -10.24      0.00
   0.00000000   0.00000000  -0.00006964          0.00 
    0.00    -10.24


     NEW-OLD atomic charge density approx. for the
potential
  NEW K-POINTS
   0.1250000   0.1250000   0.1250000   0.0625000
   0.1250000   0.1250000   0.3750000   0.1875000
   0.1250000   0.1250000   0.6250000   0.1875000
   0.1250000   0.1250000   0.8750000   0.1875000
   0.1250000   0.3750000   0.3750000   0.1875000
   0.1250000   0.3750000   0.6250000   0.3750000
   0.1250000   0.3750000   0.8750000   0.3750000
   0.1250000   0.6250000   0.6250000   0.1875000
   0.3750000   0.3750000   0.3750000   0.0625000
   0.3750000   0.3750000   0.6250000   0.1875000

     total cpu time spent up to now is     37.29 secs




	
	
		
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