[Pw_forum] VC_relax doesn't converge

[Vishal Gupta]

Hi all,
I've been running a vc_relax calculation on a 40 atom system. The
calculation works fine for some cycles. The total force had come down to
0.06108. After some time. the force started increasing monotonically. Ive
tried Gaussian broadening by using smearing=mv and tried degauss from 0.1
to 4.0D0 but there isn't much change in the minimum of force. Also, I cant
change K-points or Ecut as both of them are already at best values.
 The input file is
 /
 &SYSTEM
                       ibrav = 0,
                         nat = 40,
                        ntyp = 1,
                     ecutwfc = 12 ,
                  occupations ='smearing' ,
                    smearing='mv'
                    degauss = 0.05D0 ,

 /
 &ELECTRONS
                 mixing_beta = 0.3 ,
             mixing_mode='TF' ,
             diagonalization = 'david' ,
             electron_maxstep = 200 ,
 /

[&Ions/]
/
&CELL
cell_dynamics= 'sd' ,
cell_dofree='xy' ,
/

CELL_PARAMETERS angstrom
    22.265358047804796    0.000000000000000    0.000000000000000
     0.000000000000000   11.131216979724510    0.000000000000000
     0.000000000000000    0.000000000000000   10.000000000000000

P.S. Ive tried changing cell dynamics to 'damp-pr' , 'sd' and 'damp-w', but
the same problem persists.
Can anybody Please help me identifying the mistake ?
Thank You.
Best Regards,
Vishal Gupta

B.Tech. 3rd year Mechanical
Indian Institute of Technology Ropar
Rupnagar (140001), Punjab, India.
Email :- vishal.gupta at iitrpr.ac.in
RMML, IIT Ropar
<https://sites.google.com/a/iitrpr.ac.in/ropar-mechanics-of-materials-laboratory/people>
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