[Pw_forum] convergence w.r.t ecutwfc

[Amin Torabi]

Dear experts,

Will you please take a look at my input file and convergence table below:

I am using PBE USPP for both hydrogen and boron, but calculating energies
using PBEsol. (ecutrho is set to 12* ecutwfc.)

My question is:
1. Does it look normal? I was expect to seeing 1mRy accuracy at lower
ecutwfc values.
2. I didn't use "occupations" or "smearing" and I didn't get any error in
output files. Do they affect the convergence?
3. I want to do vc-relax calculation at high pressure. Based on my table,
what ecutwfc do you suggest?

Thanks in advance.



ecutwfc                  energy
30                       -38.28149597
35                       -38.28437812
40                       -38.28554856
45                       -38.28658930
50                       -38.28772083
55                       -38.28883141
60                       -38.28989311
65                       -38.29086868
70                       -38.29167889
75                       -38.29227767
80                       -38.29267847
85                       -38.29291696
90                       -38.29302834
95                       -38.29305836
100                      -38.29305908
105                      -38.29307545
110                      -38.29313486
115                      -38.29324982

 &control
        pseudo_dir = **
        outdir          = **
        prefix          = '$a'
        tstress         = .true
        tprnfor         = .true
        verbosity     = 'low'
 /
&SYSTEM
        ibrav             = 12
        celldm(1)       = 8.31479435
        celldm(2)       = 1.3
        celldm(3)       = 1.4772727273
        celldm(4)       = -0.260504508642648
        nat                = 16
        ntyp              = 2
        ecutwfc         = $a
        ecutrho          = `expr 12 \* $a`
        input_dft        = 'pbesol'
 /
&ELECTRONS
 /
ATOMIC_SPECIES
 B  10.811    B.pbe-n-van_ak.UPF
 H  1.00794   H.pbe-van_ak.UPF
ATOMIC_POSITIONS crystal
B        0.002   0.146   0.042
H       -0.194   0.166   0.140
H        0.196   0.294  -0.005
H        0.104  -0.019   0.112
B       -0.002  -0.146  -0.042
H        0.194  -0.166  -0.140
H       -0.196  -0.294   0.005
H       -0.104   0.019  -0.112
B        0.498   0.354   0.542
H        0.694   0.334   0.640
H        0.304   0.206   0.495
H        0.396   0.519   0.612
B        0.502   0.646   0.458
H        0.306   0.666   0.360
H        0.696   0.794   0.505
H        0.604   0.481   0.388
K_POINTS automatic
 8 8 8  0 0 0

-- 
Amin Torabi
Ph.D. Student
Chemistry Department
The University *of* Western Ontario
London, On Canada, N6A 5B7
Phone: 519-661-2111 Ext: 87871
****************************************
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