Overview: NbI₂

Structure info
Layer group	p-4m2
Layer group number	59
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.622
Heat of formation [eV/atom]	0.130
Dynamically stable	No

Basic properties
Magnetic	No
Band gap (PBE) [eV]	0.000

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	3.649	-0.000	0.000	Yes
2	-0.000	3.649	0.000	Yes
3	-0.000	0.000	19.285	No

Lengths [Å]	3.649	3.649	19.285
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Square (tp)
Layer group number	59
Layer group	p-4m2
Space group number (bulk in AA-stacking)	115
Space group (bulk in AA-stacking)	P-4m2
Point group	-42m
Inversion symmetry	No

Structure data
Formula	NbI2
Stoichiometry	AB2
Number of atoms	3
Unit cell area [Å2]	13.316
Thickness [Å]	4.137

Stability

Convex hull

NbI2 (1NbI2-3)
Heat of formation [eV/atom]	0.13
Energy above convex hull [eV/atom]	0.62

Monolayers from C2DB
Nb3I8 (1Nb3I8-1)	-0.54 eV/atom
Nb2I6 (2NbI3-1)	-0.42 eV/atom
Nb2I4 (2NbI2-1)	-0.37 eV/atom
Nb2I6 (2NbI3-2)	-0.36 eV/atom
NbI2 (1NbI2-1)	-0.18 eV/atom
NbI2 (1NbI2-2)	-0.12 eV/atom
NbI2, (1NbI2-3)	0.13 eV/atom
Nb2I2 (2INb-1)	0.14 eV/atom
Nb2I2 (2INb-2)	0.15 eV/atom

Bulk crystals from OQMD123
Nb4I16	-0.49 eV/atom
Nb2I6	-0.48 eV/atom
Nb2I10	-0.46 eV/atom
I4	0.00 eV/atom
Nb	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-6.34

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	52.28	-3.06	0.00
yy	-3.06	52.28	0.00
xy	0.00	0.00	2.38

Stiffness tensor eigenvalues
Eigenvalue 0	2.38 N/m
Eigenvalue 1	49.23 N/m
Eigenvalue 2	55.34 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.000
Direct band gap (PBE)	0.000
Fermi level wrt. vacuum (PBE)	-4.003

Fermi surface

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Nb	0.91
1	I	-0.46
2	I	-0.46

Miscellaneous

Miscellaneous details
Unique ID	1NbI2-3
Number of atoms	3
Number of species	2
Formula	NbI2
Reduced formula	NbI2
Stoichiometry	AB2
Unit cell area [Å2]	13.316
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB2/NbI2/NbI2-859d60dd1ea7
Old uid	NbI2-859d60dd1ea7
Space group (bulk in AA-stacking)	P-4m2
Space group number (bulk in AA-stacking)	115
Point group	-42m
Inversion symmetry	No
Layer group number	59
Layer group	p-4m2
2D Bravais type	Square (tp)

Miscellaneous details
Thickness [Å]	4.137
Structure origin	original03-18
Band gap (PBE) [eV]	0.000
Direct band gap (PBE) [eV]	0.000
gap_dir_nosoc	0.000
Vacuum level [eV]	3.865
Fermi level wrt. vacuum (PBE) [eV]	-4.003
minhessianeig	-6.337
Dynamically stable	No
Energy [eV]	-12.894
Magnetic	No
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]	0.622
Heat of formation [eV/atom]	0.130