ABINIT Discussion Forums

Dear all
I am trying to obtain the band structure plot for wurtzite ZnO using the following input file, But it seemed to be wrong. please help where I am wrong.
Thank you for your kindness.
Best regards.
# ZnO wurzite (hexagonal) structure
# Computation of the band structure.

ndtset 2

#Dataset 1 : usual self-consistent calculation
kptopt1 1 # Option for the automatic generation of k points,
# taking into account the symmetry
nshiftk1 1
shiftk1 0.0 0.0 0.5 # This choice of origin for the k point grid
# preserves the hexagonal symmetry of the grid,
# which would be broken by the default choice.

ngkpt1 6 6 6
prtden1 1 # Print the density, for use by dataset 2
toldfe1 1.0d-6 # This value is way too large for most realistic studies of materials

#Dataset 2 : the band structure
iscf2 -2
getden2 -1
kptopt2 -3
nband2 12
ndivk2 10 12 17 # 10, 12 and 17 divisions of the 3 segments, delimited
# by 4 points.
kptbounds2 0.0 0.0 0.0 ! G
0.06666 0.33333 0.5 ! H
0.66666 0.33333 0.0 ! K
0.0 0.0 0.0 ! G
0.0 0.5 0.0 ! M
0.0 0.5 0.5 ! L

tolwfr2 1.0d-12
enunit2 1 # Will output the eigenenergies in eV


#Definition of the unit cell
acell 6.52 6.52 9.826

angdeg 90. 90. 120.
spgroup 186

#Definition of the atom types
ntypat 2
znucl 8 30

#Definition of the atoms
natom 4
typat 1 1 2 2
xred 0.6667 0.3333 0.5000
0.3333 0.6667 0.0000
0.6667 0.3333 0.8750
0.3333 0.6667 0.3750

#Definition of the planewave basis set
ecut 20.0 # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 10 # Maximal number of SCF cycles
diemac 12.0

And pseudopotentials are : /Psps_for_tests/08-O.GGA.fhi and /Psps_for_tests/30-Zn.GGA.fhi

Hello,

Your reduced coordinates are not precise enough for abinit to find the correct symetries, you should add more decimals (I think 8 is the minimum to get the symetries) =

0.3333 => 0.3333333333
0.6667 => 0.6666666667

Or you can use also :

0.3333 => 1/3
0.6667 => 2/3

This is recognized by abinit also


David

thanks very much David for your help, it works very well, thanks

Dear nanotech

İ am studying on ZnO, i have question.

why ecut of ZnO and total energy are huge ? (mine is ecut=60 hartree and etotal~156 hartree )
for example AlAs , it look like ZnO structure (wurtzite ) and its euct is 20
and total energy is less than mine
could you give me your input , output and log file ?
i will compare them with me , and looking for mistakes

thank you

the ecut necessary for convergence is a function of the pseudopotentials you are using, not the structure. The ecut needed for an AlAs calculation is irrelevant to ZnO because the pseudopotentials are different. What pseudopotentials are you using? And, if you are really getting a positive ETOT, something is quite odd with your input, quite possibly the structure.

i used Troullier-Martins pseudopotential and my e total is pozitive 156 hartree , is this huge?

Yes, it's really huge, should be around 30-40. Something is probably wrong with your input file.

this is my ZnO.in file
****************************************************************************
#Starting approximation for the unit cell
acell 6.0569963903E+00 6.0569963903E+00 9.6994373165E+00



rprim 0.866025403784439 0.5 0.0 #hexagonal primitive vectors must be
-0.866025403784439 0.5 0.0 #specified with high accuracy to be
0.0 0.0 1.0 #and preserved in the optimization


# Definition of the atom types
ntypat 2
znucl 30 8
natom 4
typat 1 1 2 2

#Starting approximation for atomic positions in REDUCED coordinates
#based on ideal tetrahedral bond angles
xred 1/3 2/3 0.0
2/3 1/3 0.5
1/3 2/3 0.375
2/3 1/3 0.875

# Definition of the k-point grid
ngkpt 4 4 4
nshiftk 0.0 0.0 0.0
nshiftk 1

ecut: 60.0 # Maximal kinetic energy cut-off, in Hartree

# Definition of the SCF procedure
nstep 30 # Maximal number of SCF cycles
toldfe 1.0d-9 # Will stop when this tolerance is achieved on total energy
diemac 12.0

iscf 5
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