[Pw_forum] Very long time of computation

[Jun-jun Yang]

Hi,

I'm a newbie user of pwscf, and working on total energy calculation of 
chromite mineral as
my first step for getting familiar with the program. But when I run the 
program, it looks like
stpping at wavefunction calculation and seems endless.

starting charge 543.97604, renormalized to 544.00000
Starting wfc are atomic

The longest time it stopped (maybe still running) here was over 5 hours on 
one processor.
The unit cell of the mineral has 56 atoms (Z=8) and crystal system is cubic. 
I'm using USPP
potential. Please refer to snippet of my input file below. Do I make 
anything wrong? Is such
a long computation time reasonable?

&control
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='fecr2o4',
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = '../../pseudo/',
    outdir = $HOME/temp/
/
&system
    ibrav = 1, celldm(1) = 15.8321, nat = 56 , ntyp = 3,
    ecutwfc = 40.0
/
&electrons
    diagonalization = cg,
    mixing_mode = 'plain',
    mixing_beta = 0.7,
    conv_thr =  1.0d-8
/
ATOMIC_SPECIES
Fe  55.847  Fe.pbe-sp-van.UPF
Cr  51.996  Cr.pbe-sp-van.UPF
O   15.999   O.pbe-van_ak.UPF
ATOMIC_POSITIONS angstrom
Fe    0.00000    0.00000    0.00000
Cr    5.23625    5.23625    5.23625
O    3.23391    3.23391    3.23391
......
......

K_POINTS automatic
8 8 8  0 0 0

Please help and thanks in advance.


Jun-jun Yang

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