[Pw_forum] convergence test for chromium

[udayagiri sai babu]

Dear all
I did convergence tests for chromium. The ecut value i obtained for energy
converged to 1mRyd is 60Ryd! which i believe is very high for an Ultra Soft
PP can somebody tell me if i am doing something wrong. Given below are my
sample input file and ecut vs total energy.

&control
calculation = 'scf',
restart_mode='from_scratch',
outdir='/home/sai/softwares/espresso-4.0.1/workspace/temp',
prefix='chromium'
pseudo_dir='/home/sai/softwares/espresso-4.0.1/pseudo/',
/
&system
ibrav=3
celldm(1)=5.450000,
nat=1,
ntyp=1
ecutwfc=15,
ecutrho=150,
occupations='smearing',
smearing='mp',
degauss=0.005000
/
&electrons
conv_thr=1.D-8,
diagonalization='david',
mixing_mode='plain',
mixing_beta= 0.3
electron_maxstep=1000
/
ATOMIC_SPECIES
Cr  51.9961  Cr.pbe-sp-van.UPF
ATOMIC_POSITIONS (crystal)
Cr  0.00000000    0.00000000    0.00000000
K_POINTS {automatic}
12 12 12 0 0 0

ecut    energy
15    -171.52805273
20    -173.85044031
25    -174.14015464
30    -174.15592557
35    -174.16252481
40    -174.17616814
45    -174.18792735
50    -174.19506225
55    -174.19773267
60    -174.19824847

-- 
U.Saibabu
PhD student,
Deformation mechanisms modeling group,
Materials engineering department,
IISc Bangalore,
India.
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