Dear S. Arash Sheikholeslam,
your settings for the basis set seem quite low, you should consider
increasing these two values:
ecutwfc = 25.0, ecutrho = 300.0
You can check this web page
https://www.materialscloud.org/discover/sssp/plot/efficiency/Pb to
identify the appropriate basis set parameters for the pseudopotential
that you are using. The actual values to be used should be converged
according to the specific scientific case that you intend to investigate.
Reciprocal space sampling should probably also be improved.
Best regards,
Pietro
On 12/8/19 9:54 PM, sarashs wrote:
Hi quantum espresso users,
I am performing a vc-relax simulation on pb. I have included my input
file for your convenience. The problem that I have is that the minimum
energy cell is more than 1 Angstrom smaller on each dimension (3.25
Angstrom) while it should be around 4.95. I am wondering if you can help
me figure out why? I have tried increasing the number of K points,
ecutwfc and I tried with different degauss values but I was not
successful in converging to the right size.
Is this an xc functional issue? or something else?
&control
calculation = "vc-relax" ,
restart_mode = 'from_scratch' ,
outdir='$TMP_DIR/' ,
pseudo_dir = '$PSEUDO_DIR' ,
disk_io = 'default' ,
verbosity = 'default' ,
tstress = .true. ,
tprnfor = .true. ,
/
&system
ibrav = 2, celldm(1) =4.9505, nat= 1, ntyp= 1,
ecutwfc = 25.0, ecutrho = 300.0
occupations='smearing', smearing='gaussian', degauss=0.02
/
&electrons
diagonalization='david'
conv_thr = 1.0e-8
mixing_beta = 0.7
/
&IONS
/
&CELL
cell_dynamics = 'bfgs',
press = 1.00 ,
/
ATOMIC_SPECIES
Pb 207.2 Pb.pbe-dn-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS alat
Pb 0.0 0.0 0.0
K_POINTS (automatic)
5 5 5 0 0 0
Best regards,
S. Arash Sheikholeslam
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--
Pietro Bonfà
Department of Mathematical, Physical and Computer Sciences,
University of Parma,
Italy
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