[Pw_forum] Help with atomic relaxation (Issue with convergence)

[Vikas Varshney]

Dear Paolo, Giuseppe,

Thank you for all your comments. I will try to run simulations as you
suggested. In any case, this is how my input file looks if you have further
suggestions.

 &CONTROL
                 calculation = 'relax' ,
                restart_mode = 'from_scratch' ,
                  wf_collect = .true. ,
                      outdir = './' ,
                  pseudo_dir = '/lustre/app2/espresso/pseudo/' ,
                     disk_io = 'default' ,
                   verbosity = 'high' ,
 /
 &SYSTEM
                       ibrav = 0,
                    celldm(1)=   9.050787,
                         nat = 34,
                        ntyp = 3,
                     ecutwfc = 55 ,
                     ecutrho = 550 ,
                 occupations = 'smearing' ,
                     degauss = 0.01 ,
                    smearing = 'methfessel-paxton' ,
                nosym   = .true. ,
                nosym_evc = .true. ,
 /
 &ELECTRONS
                    conv_thr = 1.0D-4 ,
             diagonalization = 'david' ,
                 mixing_mode = 'local-TF' ,
                 mixing_beta = 0.1 ,
        electron_maxstep = 500 ,
 /
 &IONS
                ion_dynamics = 'bfgs' ,
               ion_positions = 'from_input' ,
 /
CELL_PARAMETERS hexagonal
     1.000000000    0.000000000    0.000000000
     0.500000000    0.866025000    0.000000000
     0.000000000    0.000000000    10.824313000
ATOMIC_SPECIES
    O   15.99940  O.pbe-van_ak.UPF
   Al   26.98154  Al.pbe-n-van.UPF
   Ni   58.69340  Ni.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS angstrom
O        1.473346033   0.017326072   3.218609176
O        3.863581042   1.378379317   7.574956508
O        1.513480866   2.829876285  11.933514340
O       -0.751677351   1.267293591   3.218609163
O        1.663968734   2.656771683   7.574956486
O       -0.812749430   4.043578468  11.933514157
O        1.673065193   2.863185205   3.218609361
O        1.656654190   0.112656124   7.574956554
O       -0.700731568   1.422153909  11.933514350
O        3.298048338   0.005706615   9.773211485
O        0.927961928   1.382600916   1.089494747    0   0   0
O       -1.464820834   2.766734881   5.396064047
O       -1.653964847   2.853342545   9.773211296
O        3.128121670   0.112338146   1.089494747    0   0   0
O        0.731082457   1.495864856   5.396064158
Al      -0.000000812   0.000001493   4.556157709
Al       2.394734647   1.382602298   8.876166342
Al       0.000000000   2.765201880   0.243870515    0   0   0
Al       0.000000000   0.000000000   1.935118618    0   0   0
Al       2.394734540   1.382602230   6.225550857
Al      -0.000000007   2.765202952  10.790402310
Al      -0.000000362   0.000002278   8.430662634
Al       2.394735475   1.382602563  12.021576409
Al      -0.000000581   2.765202130   4.047340256
Al       0.000000075   0.000002190  11.054412333
Al       2.394734840   1.382601177   2.258435418
Al      -0.000000323   2.765202460   6.730673987
  Ni      -0.016734       -0.025515       15.297379
  Ni       1.180634       -2.099417       15.297379
  Ni      -1.214101       -2.099417       15.297379
  Ni      -2.411469       -0.025515       15.297379
K_POINTS automatic
  4 4 1   0 0 0
 Best Regards,
Vikas

Computational Reseacher,
Wright Patterson Air Force Base,
Dayton, OH.



On Mon, Jan 23, 2012 at 12:29 PM, Paolo Giannozzi <giannozz at democritos.it>wrote:

>
> On Jan 23, 2012, at 17:25 , giuseppe.mattioli at mlib.ism.cnr.it wrote:
>
> >> So, I wanted to ask how I can make is equilibrate faster? Would a
> >> lower
> >> value of conv_thr (1e-4 oe 1e-5)
> >
> > Maybe, but you are going to calculate poorly converged forces on
> > ions...
>
> note however that as the structural optimization goes on, the
> convergence
> threshold for self-consistency is automatically reduced (by up to a
> factor
> "upscale" that can be specified in input; default=100). So starting
> with a
> relatively large conv_thr (although I would not recommand anything >
> 1e-5)
> may not be that bad after all
>
> P.
> ---
> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
>
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