Overview: In₂Se₂

Structure info
Layer group	c2/m11
Layer group number	18
Structure origin	exfoliated02-21
COD id of parent bulk structure	COD 1540841

Stability
Energy above convex hull [eV/atom]	0.038
Heat of formation [eV/atom]	-0.500
Dynamically stable	Yes

Basic properties
Magnetic	No
Band gap (PBE) [eV]	1.630
Band gap (HSE06) [eV]	2.254

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	4.099	0.000	0.000	Yes
2	-2.050	5.614	0.000	Yes
3	-0.000	0.000	33.096	No

Lengths [Å]	4.099	5.977	33.096
Angles [°]	90.000	90.000	110.056

Crystal structure

Symmetries
2D Bravais type	Centered rectangular (oc)
Layer group number	18
Layer group	c2/m11
Space group number (bulk in AA-stacking)	12
Space group (bulk in AA-stacking)	C2/m
Point group	2/m
Inversion symmetry	Yes

Structure data
Formula	In2Se2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	23.013
Thickness [Å]	3.386

Stability

Convex hull

In2Se2 (2InSe-3)
Heat of formation [eV/atom]	-0.50
Energy above convex hull [eV/atom]	0.04

Monolayers from C2DB
In2Se2 (2InSe-1)	-0.54 eV/atom
In2Se2 (2InSe-2)	-0.53 eV/atom
In4Se6 (2In2Se3-1)	-0.53 eV/atom
In2Se3 (1In2Se3-1)	-0.53 eV/atom
In8Se12 (4In2Se3-1)	-0.51 eV/atom
In3Se4 (1In3Se4-1)	-0.51 eV/atom
In2Se2, (2InSe-3)	-0.50 eV/atom
In2Se3 (1In2Se3-2)	-0.50 eV/atom
Se12In13 (1Se12In13-1)	-0.49 eV/atom
In2Se3 (1In2Se3-3)	-0.48 eV/atom
Se12In14 (2Se6In7-1)	-0.44 eV/atom
Se12In15 (3Se4In5-1)	-0.42 eV/atom
In2Se2 (2InSe-4)	-0.39 eV/atom
In2Se5 (1In2Se5-1)	-0.36 eV/atom
In2Se2 (2InSe-5)	-0.29 eV/atom
In2Se2 (2InSe-6)	-0.23 eV/atom
In2Se4 (2InSe2-1)	-0.22 eV/atom
InSe2 (1InSe2-1)	-0.21 eV/atom
In2Se3 (1In2Se3-4)	-0.16 eV/atom
In2Se4 (2InSe2-2)	-0.16 eV/atom
In2Se4 (2InSe2-3)	-0.11 eV/atom
In2Se4 (2InSe2-4)	-0.04 eV/atom
InSe4 (1InSe4-1)	0.04 eV/atom
Se2 (2Se-1)	0.21 eV/atom
Se2 (2Se-2)	0.29 eV/atom

Bulk crystals from OQMD123
In4Se4	-0.53 eV/atom
In12Se18	-0.53 eV/atom
In	0.00 eV/atom
Se3	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Deformation potentials

DVB [eV]	xx	yy	xy
Γ	-3.41	1.96	0.00
X	1.24	-2.48	-0.39
A1	-0.31	-2.76	0.93
Y	0.86	0.33	-0.55
kVBM	1.73	-2.13	-0.00

	xx	yy	xy
Band gap [eV]	-8.30	4.17	0.00

DCB [eV]	xx	yy	xy
Γ	-6.56	2.04	-0.00
X	-1.96	-3.44	-0.54
A1	1.50	-2.90	-0.79
Y	0.17	-3.13	0.07
kCBM	-6.56	2.04	-0.00

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	28.55	1.08	0.04
yy	1.77	31.12	-0.02
xy	-0.00	-0.00	13.38

Stiffness tensor eigenvalues
Eigenvalue 0	13.38 N/m
Eigenvalue 1	27.95 N/m
Eigenvalue 2	31.72 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	1.630
Direct band gap (PBE)	1.841
Valence band maximum wrt. vacuum (PBE)	-5.404
Conduction band minimum wrt. vacuum (PBE)	-3.775

Effective masses

Property (VBM)	Value
Min eff. mass	0.34 m0
Max eff. mass	5.57 m0
DOS eff. mass	1.37 m0
Crystal coordinates	[0.000, 0.500]
Warping parameter	-0.000
Barrier height	> 7.5 meV
Distance to barrier	> 0.0162 Å-1

Property (CBM)	Value
Min eff. mass	0.21 m0
Max eff. mass	1.16 m0
DOS eff. mass	0.49 m0
Crystal coordinates	[0.000, 0.000]
Warping parameter	0.001
Barrier height	> 27.8 meV
Distance to barrier	> 0.0162 Å-1

Electronic properties

Born charges

ZSeij	ux	uy	uz
Px	-2.51	-0.00	-0.00
Py	0.00	-2.56	0.20
Pz	-0.00	0.02	-0.27

ZInij	ux	uy	uz
Px	2.51	0.00	0.00
Py	0.00	2.56	-0.20
Pz	0.00	-0.02	0.27

ZSeij	ux	uy	uz
Px	-2.51	-0.00	-0.00
Py	-0.00	-2.56	0.20
Pz	-0.00	0.02	-0.27

ZInij	ux	uy	uz
Px	2.51	0.00	0.00
Py	0.00	2.56	-0.20
Pz	-0.00	-0.02	0.27

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Se	-0.72
1	Se	-0.72
2	In	0.72
3	In	0.72

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	2.470
Interband polarizability (y) [Å]	2.947
Interband polarizability (z) [Å]	0.365

Infrared polarizability

Static polarizability [Å]
Phonons only (x)	1.83
Phonons only (y)	2.83
Phonons only (z)	0.01
Total (phonons + electrons) (x)	4.30
Total (phonons + electrons) (y)	5.77
Total (phonons + electrons) (z)	0.38

Miscellaneous

Miscellaneous details
Unique ID	2InSe-3
Number of atoms	4
Number of species	2
Formula	In2Se2
Reduced formula	InSe
Stoichiometry	AB
Unit cell area [Å2]	23.013
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/ICSD-COD/2el/In4Se4_1
Old uid	In2Se2-0a48e35c06ea
Space group (bulk in AA-stacking)	C2/m
Space group number (bulk in AA-stacking)	12
Point group	2/m
Inversion symmetry	Yes
Layer group number	18
Layer group	c2/m11
2D Bravais type	Centered rectangular (oc)
Thickness [Å]	3.386
Structure origin	exfoliated02-21
Band gap (PBE) [eV]	1.630
Direct band gap (PBE) [eV]	1.841
gap_dir_nosoc	1.873
Vacuum level [eV]	1.504
Fermi level wrt. vacuum (PBE) [eV]	-4.590
Valence band maximum wrt. vacuum (PBE) [eV]	-5.404
Conduction band minimum wrt. vacuum (PBE) [eV]	-3.775

Miscellaneous details
minhessianeig	-0.000
Dynamically stable	Yes
Band gap (HSE06) [eV]	2.254
Direct band gap (HSE06) [eV]	2.483
Fermi level wrt. vacuum (HSE) [eV]	-4.670
Valence band maximum wrt. vacuum (HSE06) [eV]	-5.797
Conduction band minimum wrt. vacuum (HSE06) [eV]	-3.543
Interband polarizability (x) [Å]	2.470
Interband polarizability (y) [Å]	2.947
Interband polarizability (z) [Å]	0.365
Static polarizability (phonons) (x) [Å]	1.834
Static polarizability (phonons + electrons) (x) [Å]	4.304
Static polarizability (phonons) (y) [Å]	2.826
Static polarizability (phonons + electrons) (y) [Å]	5.773
Static polarizability (phonons) (z) [Å]	0.014
Static polarizability (phonons + electrons) (z) [Å]	0.379
Energy [eV]	-14.491
COD id of parent bulk structure	COD 1540841
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
Energy above convex hull [eV/atom]	0.038
Heat of formation [eV/atom]	-0.500