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Structure info
Layer group pm2m
Layer group number 27
Structure origin adhoc_material
Stability
Energy above convex hull [eV/atom] 0.000
Heat of formation [eV/atom] -1.898
Dynamically stable Yes
Basic properties
Magnetic No
Ferroelectric Yes
Band gap (PBE) [eV] 1.041
Band gap (HSE06) [eV] 1.951
  XYZ CIF JSON
Axis x [Å] y [Å] z [Å] Periodic
1 3.942 0.000 0.000 Yes
2 0.000 6.739 0.000 Yes
3 -0.000 -0.000 34.045 No
Lengths [Å] 3.942 6.739 34.045
Angles [°] 90.000 90.000 90.000

Symmetries
2D Bravais type Rectangular (op)
Layer group number 27
Layer group pm2m
Space group number (bulk in AA-stacking) 25
Space group (bulk in AA-stacking) Pmm2
Point group mm2
Inversion symmetry No
Structure data
Formula Nb2O2Cl4
Stoichiometry ABC2
Number of atoms 8
Unit cell area [Å2] 26.564
Thickness [Å] 3.886

Nb2O2Cl4 (2NbOCl2-1)
Heat of formation [eV/atom] -1.90
Energy above convex hull [eV/atom] 0.00
Monolayers from C2DB
Nb4O8 (4NbO2-1) -2.42 eV/atom
Nb2O4 (2NbO2-1) -2.38 eV/atom
NbO2 (1NbO2-1) -2.37 eV/atom
NbO2 (1NbO2-2) -2.35 eV/atom
Cl2Nb2O4 (2ClNbO2-1) -2.32 eV/atom
NbO2 (1NbO2-3) -2.20 eV/atom
Cl2Nb2O3 (1Cl2Nb2O3-1) -2.09 eV/atom
Nb2O6 (2NbO3-1) -2.07 eV/atom
Nb2O2Cl4, (2NbOCl2-1) -1.90 eV/atom
Cl2Nb2O2 (2ClNbO-1) -1.86 eV/atom
Nb4O12 (4NbO3-1) -1.83 eV/atom
Nb2O2 (2NbO-1) -1.53 eV/atom
ONb3Cl7 (1ONb3Cl7-1) -1.49 eV/atom
Nb2Cl4O4 (2NbCl2O2-1) -1.40 eV/atom
Nb3Cl8 (1Nb3Cl8-1) -1.35 eV/atom
Nb2O2 (2NbO-2) -1.30 eV/atom
Nb2Cl6 (2NbCl3-1) -1.22 eV/atom
Nb2Cl6 (2NbCl3-2) -1.19 eV/atom
NbCl4 (1NbCl4-1) -1.16 eV/atom
Nb2Cl4 (2NbCl2-1) -1.13 eV/atom
OCl2Nb2 (1OCl2Nb2-1) -1.07 eV/atom
NbCl2 (1NbCl2-1) -1.06 eV/atom
Nb2O2 (2NbO-3) -1.02 eV/atom
NbCl2 (1NbCl2-2) -0.96 eV/atom
NbCl2 (1NbCl2-3) -0.76 eV/atom
Cl2Nb2 (2ClNb-1) -0.17 eV/atom
Cl2Nb2 (2ClNb-2) -0.10 eV/atom
Bulk crystals from OQMD123
Nb2O5 -2.77 eV/atom
Nb8O16 -2.64 eV/atom
Nb3O3 -2.08 eV/atom
Cl20Nb12O8 -1.75 eV/atom
Cl12Nb4O4 -1.73 eV/atom
Cl16Nb6 -1.33 eV/atom
Cl8Nb2 -1.32 eV/atom
Cl28Nb12 -1.31 eV/atom
Cl30Nb6 -1.30 eV/atom
Cl4 0.00 eV/atom
Nb 0.00 eV/atom
O8 0.00 eV/atom
Cl8O16 0.13 eV/atom

ABC2/2NbOCl2/1/phonon_bs.png
Minimum eigenvalue of Hessian [eV/Ų] -0.00

DVB [eV] xx yy xy
Γ 1.78 4.22 0.00
X 1.41 4.04 0.00
S 1.75 -2.28 0.00
Y 2.48 -2.43 0.00
kVBM 1.75 -2.28 0.00
xx yy xy
Band gap [eV] 8.06 1.56 0.01
DCB [eV] xx yy xy
Γ 11.24 -1.66 0.01
X 0.36 -8.48 0.00
S 0.47 1.80 0.01
Y 9.81 -0.72 0.01
kCBM 9.81 -0.72 0.01

Cij (N/m) xx yy xy
xx 85.25 5.53 -0.09
yy 4.80 66.05 -0.04
xy 0.00 0.01 30.47
Stiffness tensor eigenvalues
Eigenvalue 0 30.47 N/m
Eigenvalue 1 64.76 N/m
Eigenvalue 2 86.55 N/m

cij [e/Å] xx yy xy
x 1.26 -0.02 0.00
y 0.00 -0.00 0.04
z -0.00 -0.00 -0.00
cijclamped [e/Å] xx yy xy
x -0.00 0.01 -0.00
y 0.00 0.00 0.03
z -0.00 0.00 0.00

Key values [eV]
Band gap (PBE) 1.041
Direct band gap (PBE) 1.119
Valence band maximum wrt. vacuum (PBE) -5.964
Conduction band minimum wrt. vacuum (PBE) -4.923
DOS BZ

Key values [eV]
Band gap (HSE06) 1.951
Direct band gap (HSE06) 2.030
Valence band maximum wrt. vacuum (HSE06) -6.263
Conduction band minimum wrt. vacuum (HSE06) -4.312

VBM
Property (VBM) Value
Min eff. mass 11.67 m0
Max eff. mass 25.41 m0
DOS eff. mass 15.81 m0
Crystal coordinates [0.500, 0.482]
Warping parameter -0.004
Barrier height 0.0 meV
Distance to barrier 0.00201 Å-1
CBM
Property (CBM) Value
Min eff. mass 0.19 m0
Max eff. mass 0.59 m0
DOS eff. mass 0.32 m0
Crystal coordinates [-0.000, 0.496]
Warping parameter 0.003
Barrier height > 18.8 meV
Distance to barrier > 0.0159 Å-1

ZNbij ux uy uz
Px 6.51 -0.01 0.00
Py -0.38 3.78 0.00
Pz 0.00 0.00 0.71
ZClij ux uy uz
Px -0.35 0.00 -0.13
Py -0.00 -0.51 -0.00
Pz -0.03 -0.00 -0.28
ZClij ux uy uz
Px -0.44 0.00 0.04
Py -0.00 -2.14 0.00
Pz 0.02 -0.00 -0.23
ZOij ux uy uz
Px -5.72 0.11 -0.00
Py 0.44 -1.13 0.00
Pz -0.00 -0.00 -0.20
ZClij ux uy uz
Px -0.44 -0.00 -0.04
Py 0.00 -2.14 0.00
Pz -0.02 -0.00 -0.23
ZNbij ux uy uz
Px 6.51 0.01 -0.00
Py 0.38 3.78 0.00
Pz -0.00 0.00 0.71
ZClij ux uy uz
Px -0.35 -0.00 0.13
Py 0.00 -0.51 -0.00
Pz 0.03 -0.00 -0.28
ZOij ux uy uz
Px -5.72 -0.11 0.00
Py -0.44 -1.13 0.00
Pz 0.00 -0.00 -0.20

Atom No. Chemical symbol Charges [|e|]
0 Nb 2.13
1 Cl -0.57
2 Cl -0.53
3 Nb 2.13
4 Cl -0.57
5 Cl -0.53
6 O -1.02
7 O -1.02

Spontaneous polarization vector component [pC/m] Value
Px 213.46
Py -0.00
Pz -0.00

ABC2/2NbOCl2/1/rpa-pol-x.png ABC2/2NbOCl2/1/rpa-pol-z.png
ABC2/2NbOCl2/1/rpa-pol-y.png
Properties
Interband polarizability (x) [Å] 1.556
Interband polarizability (y) [Å] 2.329
Interband polarizability (z) [Å] 0.339

ABC2/2NbOCl2/1/ir-pol-x.png ABC2/2NbOCl2/1/ir-pol-z.png
ABC2/2NbOCl2/1/ir-pol-y.png
Static polarizability [Å]
Phonons only (x) 2.67
Phonons only (y) 2.56
Phonons only (z) 0.03
Total (phonons + electrons) (x) 4.22
Total (phonons + electrons) (y) 4.89
Total (phonons + electrons) (z) 0.37

Shift-current Shift-current Shift-current Shift-current Shift-current
Element Relations
xxx
xyx xyx=xxy
xyy
xzz
yxx
yxy yxy=yyx
yyy
yzz
Others 0=xxz=xyz=xzx=xzy=yxz=yyz=yzx=yzy=zxx=zxy=zyx=zyy= zzz
zxz zxz=zzx
zyz zyz=zzy
Shift-current Shift-current Shift-current Shift-current Shift-current

Miscellaneous details
Unique ID 2NbOCl2-1
Number of atoms 8
Number of species 3
Formula Nb2O2Cl4
Reduced formula NbOCl2
Stoichiometry ABC2
Unit cell area [Å2] 26.564
Original file-system folder /home/niflheim2/cmr/C2DB-ASR/adhoc_materials/Nb2O2Cl4
Old uid Nb2O2Cl4-29323693cd83
Space group (bulk in AA-stacking) Pmm2
Space group number (bulk in AA-stacking) 25
Point group mm2
Inversion symmetry No
Layer group number 27
Layer group pm2m
2D Bravais type Rectangular (op)
Thickness [Å] 3.886
Structure origin adhoc_material
Band gap (PBE) [eV] 1.041
Direct band gap (PBE) [eV] 1.119
gap_dir_nosoc 1.120
Vacuum level [eV] 1.772
Fermi level wrt. vacuum (PBE) [eV] -5.443
Valence band maximum wrt. vacuum (PBE) [eV] -5.964
Conduction band minimum wrt. vacuum (PBE) [eV] -4.923
minhessianeig -0.000
Miscellaneous details
Dynamically stable Yes
Band gap (HSE06) [eV] 1.951
Direct band gap (HSE06) [eV] 2.030
Fermi level wrt. vacuum (HSE) [eV] -5.287
Valence band maximum wrt. vacuum (HSE06) [eV] -6.263
Conduction band minimum wrt. vacuum (HSE06) [eV] -4.312
Interband polarizability (x) [Å] 1.556
Interband polarizability (y) [Å] 2.329
Interband polarizability (z) [Å] 0.339
Static polarizability (phonons) (x) [Å] 2.669
Static polarizability (phonons + electrons) (x) [Å] 4.225
Static polarizability (phonons) (y) [Å] 2.564
Static polarizability (phonons + electrons) (y) [Å] 4.893
Static polarizability (phonons) (z) [Å] 0.028
Static polarizability (phonons + electrons) (z) [Å] 0.366
Energy [eV] -53.226
Magnetic No
Total magnetic moment [μB] 0.000
Spin axis z
Magnetic anisotropy energy, xz [meV/unit cell] 0.000
Magnetic anisotropy energy, yz [meV/unit cell] 0.000
Ferroelectric Yes
Spontaneous polarization [pC/m] 213.459
Energy above convex hull [eV/atom] 0.000
Heat of formation [eV/atom] -1.898