Differences in bandstructure in Quantum Espresso and Siesta for monolayer CrI3

Asked by Shamik Chakraborty on 2020-10-19

Hello,

I am Shamik from India.

I calculated the band structure of monolayer CrI3 in Quantum Espresso. The exchange correctional functional I used is GGA-PBE and ultrasoft pseudopotential. I found that the bands (spin-up and spin-down) match with the bands available in the literature.

When I performed the band structure calculation of monolayer CrI3 in Siesta I found that the band structure does not match with the results of Quantum Espresso. The exchange correctional functional I used is GGA-PBE.

Why this big difference should exist?

It will be very helpful if someone can help me with this question.
Also guide me in the right direction.

 I am attaching the input files for your reference.

The input files of QUANTUM ESPRESSO for SCF and BANDS calculations are as below:

#####SCF==================================================
# Output variables

WriteMullikenPop 0
WriteBands .true.
SaveRho .false.
SaveDeltaRho .false.
SaveHS .false.
SaveElectrostaticPotential .false.
SaveTotalPotential .false.
WriteCoorXmol .false.
WriteMDXmol .false.
WriteMDhistory .false.
WriteEigenvalues .true.
COOP.Write .true.
WFS.Write.For.Bands .true.
WFS.band.min 1
WFS.band.max 108

=================================================

&control
    title = 'CrI3-scf'
    calculation='scf'
    prefix='cri3-recal',
    pseudo_dir = '/home/shamik/PP'
    outdir='/home/shamik/outdir'
    wfcdir='/home/shamik/outdir'
 /
 &system
    ibrav = 12
    celldm(1) = 13.105
    celldm(2) = 1.0
    celldm(3) = 5.45 !! 20AA
    celldm(4) = -0.500000
    nat = 8
    ntyp=2,
    ecutwfc = 50,
    ecutrho = 500,
    occupations = 'smearing',
    degauss = 0.005,
    smearing = 'methfessel-paxton',
    nspin = 2, !! Spin polarized calculation
    starting_magnetization(1)=0.2
    starting_magnetization(2)=0.2
 /

 &electrons
    conv_thr = 1.D-6

 /

ATOMIC_SPECIES
Cr 52 Cr.pbe-spn-rrkjus_psl.1.0.0.UPF
I 127 I.pbe-n-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS angstrom
Cr 3.417532951 1.939314693 3.665153995
Cr -0.050109469 -0.062994414 3.666024074
I 1.185996971 1.800677388 2.093677963
I 5.653246033 1.801286764 5.237586130
I 4.402237196 3.937951692 2.082815511
I 2.182167842 0.071536554 5.236445589
I 2.431503881 3.941023207 5.249062068
I 4.651470216 0.073932995 2.095990868

K_POINTS automatic
12 12 1 0 0 0

########################################

#####BANDS

&control
    title = 'CrI3-bands'
    calculation='bands'
    prefix='cri3-recal',
    pseudo_dir = '/home/shamik/PP'
    outdir='/home/shamik/outdir'
    wfcdir='/home/shamik/outdir'
 /
 &system
    ibrav = 12
    celldm(1) = 13.105
    celldm(2) = 1.0
    celldm(3) = 5.45 !! 20AA
    celldm(4) = -0.500000
    nat = 8
    ntyp=2,
    nbnd=42,
    ecutwfc = 50,
    ecutrho = 500,
    occupations = 'smearing',
    degauss = 0.005,
    smearing = 'methfessel-paxton',
    nspin = 2, !! Spin polarized calculation
    starting_magnetization(1)=0.2
    starting_magnetization(2)=0.2
 /

 &electrons
    conv_thr = 1.D-6

 /

ATOMIC_SPECIES
Cr 52 Cr.pbe-spn-rrkjus_psl.1.0.0.UPF
I 127 I.pbe-n-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS angstrom
Cr 3.417532951 1.939314693 3.665153995
Cr -0.050109469 -0.062994414 3.666024074
I 1.185996971 1.800677388 2.093677963
I 5.653246033 1.801286764 5.237586130
I 4.402237196 3.937951692 2.082815511
I 2.182167842 0.071536554 5.236445589
I 2.431503881 3.941023207 5.249062068
I 4.651470216 0.073932995 2.095990868

K_POINTS {crystal_b}
4
   0.0000000000 0.0000000000 0.0000000000 20
  -0.3333333333 0.6666666667 0.0000000000 20
   0.0000000000 0.5000000000 0.0000000000 20
   0.0000000000 0.0000000000 0.0000000000 20

#############################################

The input files of SIESTA for SCF and BANDS calculations are as below:

SystemName cri3-scf
SystemLabel cri3-scf

==================================================
# BASIS

PAO.BasisSize DZP
PAO.EnergyShift 0.01 Ry

==================================================
# K-points

%block kgrid_Monkhorst_Pack
36 0 0 0.0
0 36 0 0.0
0 0 1 0.0
%endblock kgrid_Monkhorst_Pack

==================================================
# Geometry
%include geo_dev_cri3.fdf

==================================================
# General variables

ElectronicTemperature 900 K
MeshCutoff 300 Ry
xc.functional GGA # Exchange-correlation functional
xc.authors PBE
SpinPolarized .true.
SolutionMethod diagon

BandLinesScale ReciprocalLatticeVectors

%block BandLines
1 0.0000 0.0000 0.000 \Gamma
80 -0.3333 0.6667 0.000 K
80 0.0000 0.5000 0.000 M
80 0.000 0.000 0.000 \Gamma
%endblock BandLines

==================================================
# SCF variables

MaxSCFIterations 1000 # Maximum number of SCF iter
DM.MixingWeight 0.005 # New DM amount for next SCF cycle
DM.Tolerance 0.0001 # Tolerance in maximum difference
DM.UseSaveDM .false. # to use continuation files
DM.NumberPulay 5
Diag.DivideAndConquer no
Diag.ParallelOverK yes
==================================================
# MD variables

MD.FinalTimeStep 1
MD.TypeOfRun CG
MD.NumCGsteps 000
MD.UseSaveXV .false.

==================================================
==================================================
# Output variables

WriteMullikenPop 0
WriteBands .true.
SaveRho .false.
SaveDeltaRho .false.
SaveHS .false.
SaveElectrostaticPotential .false.
SaveTotalPotential .false.
WriteCoorXmol .false.
WriteMDXmol .false.
WriteMDhistory .false.
WriteEigenvalues .true.
COOP.Write .true.
WFS.Write.For.Bands .true.
WFS.band.min 1
WFS.band.max 108

=================================================

Thank You
~Shamik

Question information

Language:
English Edit question
Status:
Expired
For:
Siesta Edit question
Assignee:
No assignee Edit question
Last query:
2020-10-19
Last reply:
2020-11-04
Alberto Garcia (albertog) said : #1

Hi,

You do not show the band structures, so we cannot gauge what you describe as "large differences". Also, you do not give any information about the pseudopotentials you are using for Siesta, neither about whether you have done any research on choosing a good basis set.

Dear Prof. Alberto Garcia,

Sorry, I forgot to attach the figures for the bands.

I was unable to find any options to attach a screenshot in the forum. So I could only attach them in a mail and send it to you.

The pseudopotential files I chose for SIESTA are taken from GGA Pseudopotential Database (https://departments.icmab.es/leem/SIESTA_MATERIAL/Databases/Pseudopotentials/periodictable-gga-abinit.html)

I used the basis set - DZP for band calculations in SIESTA. Is it suitable for ferromagnetic semiconductors like CrI3?

Launchpad Janitor (janitor) said : #4

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Nick Papior (nickpapior) said : #5

Hi,

Yeah. You should try and create your own pseudopotentials and then optimize basis set.
Using the ones from the data-base are not advisable without extreme care.