[QE-users] Wrong position of fermi level in bulk Cr2O3
Yuvam Bhateja
yuvamb16 at gmail.com
Thu Jul 23 12:43:43 CEST 2020
Hello dear experts,
Hope you are doing well.
I was trying to calculate the DOS in hexagonal Cr2O3, the DOS is coming
very well with a bandgap of 3.09, but the problem is the Fermi level is at
the edge of LUMO whereas I've observed that it should be at HUMO edge in
few already published papers.
I used PBE NC SR pseudopotential and also optimized with the same. I used
gaussian smearing with a width of 0.001 in VC-relax and tetrahedra in SCF
calculation.
Here is my input file -
&CONTROL
calculation = "scf"
pseudo_dir = "./"
outdir = "./outdir"
/
&SYSTEM
a = 4.6166825e+00
c = 1.2457778e+01
ecutrho = 4.5000e+02
ecutwfc = 4.5000e+01
ibrav = 4
nat = 30
nspin = 2
ntyp = 3
nbnd = 276
starting_magnetization(1) = 0.5
starting_magnetization(2) = -0.5
starting_magnetization(3) = 0.0
tot_magnetization = 0.0
lda_plus_u = .true.
Hubbard_U(1) = 4.7
Hubbard_U(2) = 4.7
Hubbard_J0(1) = 1
Hubbard_J0(2) = 1
/
&ELECTRONS
conv_thr = 1.00000e-11
electron_maxstep = 2000
mixing_beta = 7.00000e-01
startingpot = "atomic"
startingwfc = "atomic+random"
/
K_POINTS {automatic}
12 12 12 0 0 0
ATOMIC_SPECIES
Cr1 51.99610 Cr.upf
Cr2 51.99610 Cr.upf
O 15.99940 O.upf
ATOMIC_POSITIONS (angstrom)
Cr2 -0.0000027528 2.6654550870 3.9638155751
Cr1 2.3083528721 1.3327252495 2.2651020880
Cr1 -0.0000027528 2.6654550870 0.1887989665
Cr2 0.0000000000 0.0000000000 1.8875092202
Cr2 0.0000000000 0.0000000000 8.1164268017
Cr1 -0.0000027528 2.6654550870 6.4177165986
Cr1 0.0000000000 -0.0000000000 4.3414084067
Cr2 2.3083528721 1.3327252495 6.0401185402
Cr2 2.3083528721 1.3327252495 12.2690363475
Cr1 0.0000000000 0.0000000000 10.5703258606
Cr1 2.3083528721 1.3327252495 8.4940197683
Cr2 -0.0000027528 2.6654550870 10.1927331413
O 1.4445126756 0.0000000398 3.1144588851
O 3.0306076646 0.0817435268 1.0381518347
O 0.8638388763 1.3327251470 1.0381518347
O 3.0306056520 2.5837116627 1.0381518347
O -0.7222568310 1.2509851988 3.1144588851
O 1.5860942747 2.7471960155 3.1144588851
O 3.7528623252 1.3327254382 7.2670694393
O 0.7222547656 1.4144695631 5.1907658203
O -1.4445122603 2.6654550733 5.1907658203
O 0.7222574947 3.9164369542 5.1907658203
O 1.5860961469 2.5837115564 7.2670694393
O 1.5860937210 0.0817433419 7.2670694393
O 1.4445122976 2.6654551364 11.4196834856
O -1.5860942579 2.7471959172 9.3433763434
O 0.8638382678 3.9981804108 9.3433763434
O 0.7222569078 1.2509852624 9.3433763434
O -0.7222575680 3.9164369549 11.4196834856
O -0.7222547296 1.4144694992 11.4196834856
I later tried with pw91 USPP, it fixed the fermi level position (it's now
at HUMO edge) but the bad gap is now very underestimated to 2.3 eV.
I tried paw but it wasn't working with me.
Can someone please help?
Regards
Yuvam Bhateja
IIEST Shibpur
India
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