Overview: Nb₂S₂

Structure info
Layer group	p-3m1
Layer group number	72
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.323
Heat of formation [eV/atom]	-0.723
Dynamically stable	Yes

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	3.950	0.000	0.000	Yes
2	-1.975	3.421	0.000	Yes
3	-0.000	0.000	18.856	No

Lengths [Å]	3.950	3.950	18.856
Angles [°]	90.000	90.000	119.998

Crystal structure

Symmetries
2D Bravais type	Hexagonal (hp)
Layer group number	72
Layer group	p-3m1
Space group number (bulk in AA-stacking)	164
Space group (bulk in AA-stacking)	P-3m1
Point group	-3m
Inversion symmetry	Yes

Structure data
Formula	Nb2S2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	13.511
Thickness [Å]	3.450

Stability

Convex hull

Nb2S2 (2NbS-2)
Heat of formation [eV/atom]	-0.72
Energy above convex hull [eV/atom]	0.32

Monolayers from C2DB
Nb7S12 (1Nb7S12-1)	-1.17 eV/atom
Nb8S12 (4Nb2S3-1)	-1.17 eV/atom
Nb9S12 (3Nb3S4-1)	-1.13 eV/atom
Nb7S12 (1Nb7S12-2)	-1.10 eV/atom
NbS2 (1NbS2-1)	-1.08 eV/atom
Nb4S6 (2Nb2S3-1)	-1.05 eV/atom
NbS2 (1NbS2-2)	-1.05 eV/atom
Nb8S12 (4Nb2S3-2)	-1.05 eV/atom
Nb4S12 (4NbS3-1)	-0.82 eV/atom
Nb4S12 (4NbS3-2)	-0.82 eV/atom
Nb2S6 (2NbS3-1)	-0.80 eV/atom
Nb2S2 (2NbS-1)	-0.77 eV/atom
Nb2S2, (2NbS-2)	-0.72 eV/atom
S2Nb4 (2SNb2-1)	-0.69 eV/atom
NbS2 (1NbS2-3)	-0.68 eV/atom
Nb2S2 (2NbS-3)	-0.64 eV/atom
Nb2S2 (2NbS-4)	-0.57 eV/atom
Nb2S2 (2NbS-5)	-0.49 eV/atom
Nb2S2 (2NbS-6)	-0.47 eV/atom
S2 (2S-1)	0.45 eV/atom
S2 (2S-2)	0.62 eV/atom

Bulk crystals from OQMD123
Nb6S8	-1.18 eV/atom
NbS2	-1.08 eV/atom
Nb4S12	-0.81 eV/atom
Nb21S8	-0.61 eV/atom
Nb	0.00 eV/atom
S48	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	83.86	78.16	-0.02
yy	77.96	83.81	-0.03
xy	-0.00	-0.00	6.56

Stiffness tensor eigenvalues
Eigenvalue 0	5.78 N/m
Eigenvalue 1	6.56 N/m
Eigenvalue 2	161.89 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)	-3.843

Fermi surface

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	S	-1.06
1	S	-1.06
2	Nb	1.06
3	Nb	1.06

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	12.810
Interband polarizability (y) [Å]	13.061
Interband polarizability (z) [Å]	0.381
Plasma frequency (x) [eV Å0.5]	4.558
Plasma frequency (y) [eV Å0.5]	4.581

Raman spectrum

Mode	Frequency (1/cm)	Degeneracy
Mode 1	0.	3
Mode 2	125.6	2
Mode 3	269.9	1
Mode 4	325.2	1
Mode 5	339.	2
Mode 6	364.3	1
Mode 7	382.5	2

Miscellaneous

Miscellaneous details
Unique ID	2NbS-2
Number of atoms	4
Number of species	2
Formula	Nb2S2
Reduced formula	NbS
Stoichiometry	AB
Unit cell area [Å2]	13.511
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB/NbS/Nb2S2-31254123feb9
Old uid	Nb2S2-31254123feb9
Space group (bulk in AA-stacking)	P-3m1
Space group number (bulk in AA-stacking)	164
Point group	-3m
Inversion symmetry	Yes
Layer group number	72
Layer group	p-3m1
2D Bravais type	Hexagonal (hp)
Thickness [Å]	3.450
Structure origin	original03-18
Band gap (PBE) [eV]	0.000

Miscellaneous details
Direct band gap (PBE) [eV]	0.000
gap_dir_nosoc	0.000
Vacuum level [eV]	3.994
Fermi level wrt. vacuum (PBE) [eV]	-3.843
minhessianeig	-0.000
Dynamically stable	Yes
Interband polarizability (x) [Å]	12.810
Interband polarizability (y) [Å]	13.061
Interband polarizability (z) [Å]	0.381
Plasma frequency (x) [eV Å0.5]	4.558
Plasma frequency (y) [eV Å0.5]	4.581
Energy [eV]	-31.700
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]	0.323
Heat of formation [eV/atom]	-0.723