Hi pwscf guys,<br><br>I have done some calculations on Co impurities in ZnO. I tried to fit U_Co in such a<br>way that the caluclated Co-d projected DOS to fit experiment<br>(J. Appl. Phys. 103 07D130 (2008)). In this paper, they also fit U_Co.<br>
They use VASP. The problem is that the optimal U for pwscf and VASP differ<br>quite a lot.<br><br>I found a projected DOS similar to the one in the above paper for<br clear="all">U_Co = 0.5eV which is much smaller than their value (5.5eV with VASP). <br>
If I use their value, I get a Co-d projected DOS far deep into the valence <br>
(completely non sense).<br><br>Any idea why the optimal U values for Co in this case are so different?<br>Unfortunately, their value is more common (most transition metals around 5eV).<br>Is it the different implementations for VASP and pwscf? Pseudopotential?<br>
<br>I have already tried to publish our results but the referees can not accept the publication<br>based on such a small U_Co value.<br><br>Interestingly, my fitted value is very similar to the one determined self consistently by<br>
Hu et al, PRB 73, 245205 (2006) for the same system (0.35 eV). However, a referee thinks that <br>these small U numbers are "eroneous".<br><br>I include a typical input file with just 8 k points.<br><br>Thanks<br>
Nektarios <br>--------INPUT------------------------------------<br> &control<br> title = 'zno',<br> calculation = 'scf',<br> nstep = 200<br> restart_mode = 'from_scratch',<br>
prefix = 'zno',<br> pseudo_dir = '/usr/espresso-4.0/pseudo/',<br> outdir = '/home/lat/tmp/',<br> etot_conv_thr = 1.d-5,<br> wf_collect = .true.<br> /<br>
&system <br> ibrav = 0, <br> celldm(1) = 12.4172 , <br> nat = 16, <br> ntyp = 3,<br> ecutwfc = 50.0, <br> nosym = .true. ,<br> nbnd = 80 ,<br>
occupations = 'smearing',<br> degauss = 1.d-3,<br>starting_magnetization(3)=1,<br> nspin=2<br>lda_plus_u=.true.<br>Hubbard_U(1)=6.5<br>Hubbard_U(2)=0.0<br>Hubbard_U(3)=0.5<br>
/<br>
&electrons<br> electron_maxstep = 400,<br> diagonalization = 'david',<br> mixing_mode = 'plain',<br> mixing_beta = 0.3, <br> conv_thr = 1.0d-6<br> /<br>&IONS<br> pot_extrapolation = "second_order",<br>
wfc_extrapolation = "second_order",<br>/<br>ATOMIC_SPECIES<br> Zn 65.38000 Zn.pbe-van.UPF <br> O 15.99900 O.pbe-rrkjus.UPF<br> Co 58.93320 Co.pbe-nd-rrkjus.UPF<br>CELL_PARAMETERS<br>0.500000 0.866025 0.000000<br>
.5000000 -.8660250 0.000000<br>0.000000 0.000000 .8050500<br>ATOMIC_POSITIONS crystal<br> Zn .1666666 .3333333 .0000000 0 0 0<br> O .1666666 .3333333 .3792000 0 0 0<br> Zn .3333333 .1666666 .5000000 0 0 0<br> O .3333333 .1666666 .8792000 0 0 0<br>
Zn .6666666 .3333333 .0000000 0 0 0<br> O .6666666 .3333333 .3792000 0 0 0<br> Zn .8333333 .1666666 .5000000 0 0 0<br> O .8333333 .1666666 .8792000 0 0 0<br> Zn .1666666 .8333333 .0000000 0 0 0<br> O .1666666 .8333333 .3792000 0 0 0<br>
Co .3333333 .6666666 .5000000 0 0 0<br> O .3333333 .6666666 .8792000 0 0 0<br> Zn .6666666 .8333333 .0000000 0 0 0<br> O .6666666 .8333333 .3792000 0 0 0<br> Zn .8333333 .6666666 .5000000 0 0 0<br> O .8333333 .6666666 .8792000 0 0 0<br>
K_POINTS automatic<br>2 2 2 0 0 0<br clear="all"><br>-- <br>--------------------------------------------------------------------<br>Dr. Nektarios N. Lathiotakis<br>--------------------------------------------------------------------<br>
Theoretical and Physical Chemistry Institute<br>National Hellenic Research Foundation<br>Vass. Constantinou 48, GR-11635,<br>Athens, Greece<br>--------------------------------------------------------------------<br>Tel: +30 210 7273805 FAX: +30 210 7273794<br>
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