[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 MoujaesUniversity of NottUniversity Park NGT 3RD
 		 	   		  
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