PDOS and Bandstructure

Total energy, geometry optimization, DFT+U, spin....

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Fatmala
Posts: 1
Joined: Thu Jan 25, 2018 5:11 am

PDOS and Bandstructure

Post by Fatmala » Thu Jan 25, 2018 8:11 am

Dear all,
i'm a student and i have some problem with input file that not match with my output. there is some data of Bandstructure that not apearence in the PDOS. i hope there is anyone that could help me.
This my input file.
# Crystalline silicon
#
# Computation of the band structure.
# First, a SCF density computation, then a non-SCF band structure calculation.

ndtset 3

#Dataset 1 : usual self-consistent calculation
kptopt1 1 # Option for the automatic generation of k points,
# taking into account the symmetry
nshiftk1 4
shiftk1 0.5 0.5 0.5 # These shifts will be the same for all grids
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
ngkpt1 4 4 4
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 8
ndivk2 10 12 17 # 10, 12 and 17 divisions of the 3 segments, delimited
# by 4 points.
kptbounds2 0.5 0.0 0.0 # L point
0.0 0.0 0.0 # Gamma point
0.0 0.5 0.5 # X point
1.0 1.0 1.0 # Gamma point in another cell.
tolwfr2 1.0d-12
enunit2 1 # Will output the eigenenergies in eV

# dataset 3 pdos
iscf3 -3
getden3 -1
getwfk3 -1
prtdos3 3
dosdeltae3 0.00005
ngkpt3 4 4 4
tolwfr3 1.0d-12

#Definition of the unit cell
acell 3*10.216 # This is equivalent to 10.216 10.216 10.216
rprim 0.0 0.5 0.5 # FCC primitive vectors (to be scaled by acell)
0.5 0.0 0.5
0.5 0.5 0.0

#Definition of the atom types
ntypat 1 # There is only one type of atom
znucl 14 # The keyword "znucl" refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the "files" file must correspond
# to the type(s) of atom. Here, the only type is Silicon.


#Definition of the atoms
natom 2 # There are two atoms
typat 1 1 # They both are of type 1, that is, Silicon.
xred # This keyword indicate that the location of the atoms
# will follow, one triplet of number for each atom
0.0 0.0 0.0 # Triplet giving the REDUCED coordinate of atom 1.
1/4 1/4 1/4 # Triplet giving the REDUCED coordinate of atom 2.

#Definition of the planewave basis set
ecut 8.0 # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 10 # Maximal number of SCF cycles
diemac 12.0 # Although this is not mandatory, it is worth to
# precondition the SCF cycle. The model dielectric
# function used as the standard preconditioner
# is described in the "dielng" input variable section.
# Here, we follow the prescription for bulk silicon.

chksymbreak 0






and this is my output file, maybe you can see this file to analysis my problem.
https://drive.google.com/open?id=1dhhfn ... nD6Ldo-9H7

Thanks for your attention and for your help.

Annelinde
Posts: 6
Joined: Tue Jul 03, 2018 2:32 pm

Re: PDOS and Bandstructure

Post by Annelinde » Thu Jul 26, 2018 12:06 pm

Hi,

The projection is done in spheres around these atoms. When you want to fill a space with spheres, either you have an overlap (which causes some levels to be accounted for in multiple atoms), or you have some space in between the spheres that just isn't taken into account. It is normal to not have your spheres overlap, if you want to experiment with the sphere radius you can use the parameter ratsph.

If you sum all PDOS parts and compare this to the normal DOS curve, you'll notice some states missing, this is fairly normal.

With kind regards,

Annelinde

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