[Pw_forum] problems with vc-relax

[Elie Moujaes]

Dear
all,

 

I am relaxing a 60 atom
supercell (graphene grain boundary) to make the total force on atoms mainly
0.001 Ry/au. However the vc-relax stopped after 4 days of execution and without
reaching the desired force threshold. The following output was obtained :

 

1st relaxation process:

 

Total force 0.091  
Pressure =- 114.1 kbar

 

2nd relaxation process:

 

total force 0.1  
Pressure = -55 kbar

 

(new enthalpy < old
enthalpy)

 

3rd process: 

 

total force = 0.058
  pressure = -11 kbar

 

Then in the 4th process,
calculations stopped. Here are the last few lines of the output:

 

iteration #  2     ecut=    36.75 Ry     beta=0.30

     Davidson diagonalization
with overlap

     c_bands:  5 eigenvalues not converged

     c_bands:  1 eigenvalues not converged

     c_bands:  3 eigenvalues not converged

     c_bands:  1 eigenvalues not converged

     c_bands:  4 eigenvalues not converged

     c_bands:  4 eigenvalues not converged

     c_bands:  4 eigenvalues not converged

     c_bands:  4 eigenvalues not converged

     c_bands:  5 eigenvalues not converged

     c_bands:  5 eigenvalues not converged

     c_bands:  2 eigenvalues not converged

     c_bands:  2 eigenvalues not converged

     ethr =  2.90E-04,  avg # of iterations =
17.6



     negative rho (up,
down):  0.132E-01 0.000E+00



     total cpu time spent up
to now is 382283.13 secs



     total
energy              =    -676.77947904
Ry

     Harris-Foulkes
estimate   =    -676.82846513 Ry

     estimated scf
accuracy    <       0.17363554 Ry



     iteration #  3     ecut=    36.75 Ry     beta=0.30

     Davidson diagonalization
with overlap

     c_bands:  1 eigenvalues not converged

     c_bands:  1 eigenvalues not converged

     c_bands:  2 eigenvalues not converged

     c_bands:  3 eigenvalues not converged

 

The input of the
vc-relax is:

 

&control

    prefix='GBphonon',

    calculation='vc-relax',

    restart_mode='from_scratch',

    tstress=.true.,

    tprnfor=.true,

    pseudo_dir =
'/exp/home/caiapo/emoujaes/espresso/espresso-4.3/Pseudo/',

    outdir='/exp/home/caiapo/emoujaes/espresso/Moujaes-Results/',

         

 /

 &system   

    ibrav= 0, celldm(1) =1.889725989, nat=60, ntyp= 1, ecutwfc
=36.749309, occupations='smearing', smearing='mp',degauss=0.01

/

 &electrons

    conv_thr=1.D-6,    

    mixing_beta=0.3D0,

    diago_david_ndim=2,

     

 /

 

&ions

 ion_dynamics='bfgs'

 

/

$cell

cell_dynamics='bfgs',

 

/

 

CELL_PARAMETERS (alat)

  24.064488464   0.000772242   0.000000000

   0.000000000   6.503051170   0.000000000

   0.000000000   0.000000000   8.470514812

 

    

ATOMIC_SPECIES

 C  12.0107  C.blyp-mt.UPF

 

ATOMIC_POSITIONS
(angstrom)

C      -11.330758616  -3.527803203   0.000000000

C      -10.659793092  -1.160339161   0.000000000

C      -12.039843315  -7.112619698   0.000000000

C      -12.041158182  -5.732701936   0.000000000

C      -10.941089654  -4.881442842   0.000000000

......

 

Please can anyone advice
me on this? Shall I start with the new configuration and start relaxing again?

 

Regards

 

Elie Moujaes

University of Nott

University Park 

NGT 3RD

 
 		 	   		  
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