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Structure info
Layer group p-3m1
Layer group number 72
Structure origin original03-18
Stability
Energy above convex hull [eV/atom] 0.298
Heat of formation [eV/atom] -0.506
Dynamically stable Yes
Basic properties
Magnetic No
Band gap (PBE) [eV] 0.000
XYZ CIF JSON
Axis x [Å] y [Å] z [Å] Periodic
1 4.050 0.000 0.000 Yes
2 -2.025 3.508 0.000 Yes
3 -0.000 0.000 18.856 No
Lengths [Å] 4.050 4.051 18.856
Angles [°] 90.000 90.000 119.995

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 Nb2Se2
Stoichiometry AB
Number of atoms 4
Unit cell area [Å2] 14.211
Thickness [Å] 3.789

Nb2Se2 (2NbSe-2)
Heat of formation [eV/atom] -0.51
Energy above convex hull [eV/atom] 0.30
Monolayers from C2DB
Nb7Se12 (1Nb7Se12-1) -0.90 eV/atom
Nb8Se12 (4Nb2Se3-1) -0.88 eV/atom
NbSe2 (1NbSe2-1) -0.88 eV/atom
Nb4Se6 (2Nb2Se3-1) -0.87 eV/atom
Nb7Se12 (1Nb7Se12-2) -0.85 eV/atom
NbSe2 (1NbSe2-2) -0.85 eV/atom
Nb9Se12 (3Nb3Se4-1) -0.82 eV/atom
Nb8Se12 (4Nb2Se3-2) -0.80 eV/atom
Nb9Se12 (3Nb3Se4-2) -0.75 eV/atom
Nb4Se12 (4NbSe3-1) -0.70 eV/atom
Nb2Se6 (2NbSe3-1) -0.67 eV/atom
Se2Nb4 (2SeNb2-1) -0.55 eV/atom
Nb2Se2 (2NbSe-1) -0.53 eV/atom
Nb2Se2, (2NbSe-2) -0.51 eV/atom
Nb2Se2 (2NbSe-3) -0.46 eV/atom
NbSe2 (1NbSe2-3) -0.44 eV/atom
Nb2Se2 (2NbSe-4) -0.25 eV/atom
Nb2Se2 (2NbSe-5) -0.23 eV/atom
Se2 (2Se-1) 0.21 eV/atom
Se2 (2Se-2) 0.29 eV/atom
Bulk crystals from OQMD123
Nb6Se8 -0.91 eV/atom
Nb4Se8 -0.88 eV/atom
Nb6Se18 -0.69 eV/atom
Nb8Se4 -0.55 eV/atom
Nb4Se18 -0.54 eV/atom
Nb 0.00 eV/atom
Se3 0.00 eV/atom

AB/2NbSe/2/phonon_bs.png
Minimum eigenvalue of Hessian [eV/Ų] -0.00

Cij (N/m) xx yy xy
xx 69.46 65.54 -0.00
yy 65.30 69.31 -0.01
xy 0.00 0.00 5.15
Stiffness tensor eigenvalues
Eigenvalue 0 3.96 N/m
Eigenvalue 1 5.15 N/m
Eigenvalue 2 134.81 N/m

Key values [eV]
Band gap (PBE) 0.000
Direct band gap (PBE) 0.000
Fermi level wrt. vacuum (PBE) -3.986
DOS BZ

AB/2NbSe/2/fermi_surface.png

Atom No. Chemical symbol Charges [|e|]
0 Se -0.88
1 Se -0.88
2 Nb 0.88
3 Nb 0.88

AB/2NbSe/2/rpa-pol-x.png AB/2NbSe/2/rpa-pol-z.png
AB/2NbSe/2/rpa-pol-y.png
Properties
Interband polarizability (x) [Å] 11.578
Interband polarizability (y) [Å] 11.661
Interband polarizability (z) [Å] 0.420
Plasma frequency (x) [eV Å0.5] 5.348
Plasma frequency (y) [eV Å0.5] 5.379

AB/2NbSe/2/Raman.png
Mode Frequency (1/cm) Degeneracy
Mode 1 0. 3
Mode 2 93.7 2
Mode 3 189.2 1
Mode 4 233. 2
Mode 5 267.4 1
Mode 6 286. 1
Mode 7 294.3 2

Miscellaneous details
Unique ID 2NbSe-2
Number of atoms 4
Number of species 2
Formula Nb2Se2
Reduced formula NbSe
Stoichiometry AB
Unit cell area [Å2] 14.211
Original file-system folder /home/niflheim2/cmr/C2DB-ASR/tree/AB/NbSe/Nb2Se2-c68c118e4d1a
Old uid Nb2Se2-c68c118e4d1a
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] 3.789
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] 4.120
Fermi level wrt. vacuum (PBE) [eV] -3.986
minhessianeig -0.000
Dynamically stable Yes
Interband polarizability (x) [Å] 11.578
Interband polarizability (y) [Å] 11.661
Interband polarizability (z) [Å] 0.420
Plasma frequency (x) [eV Å0.5] 5.348
Plasma frequency (y) [eV Å0.5] 5.379
Energy [eV] -29.643
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] 0.298
Heat of formation [eV/atom] -0.506