[Pw_forum] vc-relax

[hania djani-ait aissa]

Dear all,
i am doing calculation on orthorombic system containing 36 atoms (Bi2WO6). My computer is a workstation HP xw6400 quad-core Xeon, 2GB. Vc-relax on this system spent more than 01 mounth and still not finish. the energy is converging but  forces fluctuate. is there something wrong in my input in terms of umass or dt? or have i to capitulate to this very slow convergence?
here is the input file. Any suggestions will welcome. 
&control    calculation  = 'vc-relax'    restart_mode = 'from_scratch'    pseudo_dir   = '/root/pwscf/pseudo/'    outdir       = '/root/tmp/'    tstress      = .TRUE.    tprnfor      = .TRUE.    nstep        = 55    etot_conv_thr= 1e-5,    forc_conv_thr= 1e-4,    dt           = 30, / &system    ibrav=8    celldm(1)=10.37,     celldm(2)=0.996,     celldm(3)=3.00,     nat=36    ntyp=3    ecutwfc=35.0    ecutrho=200.0,   / &electrons    conv_thr = 1e-8,    mixing_beta=0.7, / &ions /&cell    cell_dynamics = 'damp-w',    press         = 0.00,    wmass         = 0.004,/  ATOMIC_SPECIES    W     183.84    W.pz-bhs.UPF  Bi    208.98    083-Bi-ca-d-vgrp_ji.uspp.UPF  O     15.9994   O.pz-van_ak.UPF ATOMIC_POSITIONS alatW        0.000000000   0.005016973   0.747761262  0 1 1W        0.500000000   0.990983027   2.252238738  0 1 1W        0.500000000   0.492983027   0.747761262  0 1 1W        0.000000000   0.503016973   2.252238738  0 1 1Bi       0.964931181   0.523336245   1.268793038Bi       0.464931181   0.472663755   1.731206962Bi       0.464931181   0.970663755   1.268793038Bi       0.964931181   0.025336245   1.731206962Bi       0.981726782   0.473760364   0.230569958Bi       0.481726782   0.522239636   2.769430042Bi       0.481726782   0.024239636   0.230569958Bi       0.981726782   0.971760364   2.769430042O        0.100459245   0.081203101   0.435231801O        0.600459245   0.914796899   2.564768199O        0.600459245   0.416796899   0.435231801O        0.100459245   0.579203101   2.564768199O        0.264260826   0.262143525   3.000064967O        0.764260826   0.733856475  -0.000064967O        0.764260826   0.235856475   3.000064967O        0.264260826   0.760143525  -0.000064967O        0.247153777   0.235070329   1.501190932O        0.747153777   0.760929671   1.498809068O        0.747153777   0.262929671   1.501190932O        0.247153777   0.733070329   1.498809068O        0.283152650   0.701520345   0.680189839O        0.783152650   0.294479655   2.319810161O        0.783152650   0.792479655   0.680189839O        0.283152650   0.203520345   2.319810161O        0.335776234   0.239505837   0.816308565O        0.835776234   0.756494163   2.183691435O        0.835776234   0.258494163   0.816308565O        0.335776234   0.737505837   2.183691435O        0.586065178   0.587540848   1.058853940O        0.086065178   0.408459152   1.941146060O        0.086065178   0.906459152   1.058853940O        0.586065178   0.089540848   1.941146060 K_POINTS {automatic}  5 5 5 1 1 1 
thanks a lot
 
Hania Djani-ait aissa
PHD student
Algeria
 
 
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