Structure info
Layer group p-3m1
Layer group number 72
Structure origin original03-18
Stability
Energy above convex hull [eV/atom] 0.555
Heat of formation [eV/atom] -0.250
Dynamically stable No
Basic properties
Magnetic Yes
Band gap (PBE) [eV] 0.000
XYZ CIF JSON
Axis x [Å] y [Å] z [Å] Periodic
1 3.329 -0.000 0.000 Yes
2 -1.664 2.883 0.000 Yes
3 0.000 0.000 20.984 No
Lengths [Å] 3.329 3.329 20.984
Angles [°] 90.000 90.000 119.999

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] 9.596
Thickness [Å] 5.988

Nb2Se2 (2NbSe-4)
Heat of formation [eV/atom] -0.25
Energy above convex hull [eV/atom] 0.55
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/4/phonon_bs.png
Minimum eigenvalue of Hessian [eV/Ų] -1.32

Cij (N/m) xx yy xy
xx 151.24 -33.45 0.07
yy 119.41 9.81 0.08
xy 2.86 -1.88 79.24
Stiffness tensor eigenvalues
Eigenvalue 0 48.81 N/m
Eigenvalue 1 79.23 N/m
Eigenvalue 2 112.24 N/m

Property Value
Total magnetic moment [μB] 0.351
Magnetic anisotropy energy, xz [meV/unit cell] 0.029
Magnetic anisotropy energy, yz [meV/unit cell] 0.029
Heisenberg model Value
Nearest neighbor exchange coupling [meV] 17.657
Single-ion anisotropy (out-of-plane) [meV] 0.000
Anisotropic exchange (out-of-plane) [meV] -0.009
Maximum value of Sz at magnetic sites 0.500
Number of nearest neighbors 1
Atom index Atom type Local spin magnetic moment (μB) Local orbital magnetic moment (μB)
0 Nb 0.105 -0.025
1 Se 0.012 -0.000
2 Se 0.012 -0.000
3 Nb 0.105 -0.025

Key values [eV]
Band gap (PBE) 0.000
Direct band gap (PBE) 0.000
Fermi level wrt. vacuum (PBE) -4.692
DOS BZ

AB/2NbSe/4/fermi_surface.png

Atom No. Chemical symbol Charges [|e|]
0 Nb 0.69
1 Se -0.68
2 Se -0.68
3 Nb 0.68

AB/2NbSe/4/rpa-pol-x.png AB/2NbSe/4/rpa-pol-z.png
AB/2NbSe/4/rpa-pol-y.png
Properties
Interband polarizability (x) [Å] 116.210
Interband polarizability (y) [Å] 118.172
Interband polarizability (z) [Å] 0.623
Plasma frequency (x) [eV Å0.5] 5.339
Plasma frequency (y) [eV Å0.5] 5.355

Miscellaneous details
Unique ID 2NbSe-4
Number of atoms 4
Number of species 2
Formula Nb2Se2
Reduced formula NbSe
Stoichiometry AB
Unit cell area [Å2] 9.596
Original file-system folder /home/niflheim2/cmr/C2DB-ASR/tree/AB/NbSe/Nb2Se2-953130c3a422
Old uid Nb2Se2-953130c3a422
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] 5.988
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] 5.542
Miscellaneous details
Fermi level wrt. vacuum (PBE) [eV] -4.692
minhessianeig -1.317
Dynamically stable No
Interband polarizability (x) [Å] 116.210
Interband polarizability (y) [Å] 118.172
Interband polarizability (z) [Å] 0.623
Plasma frequency (x) [eV Å0.5] 5.339
Plasma frequency (y) [eV Å0.5] 5.355
Energy [eV] -28.617
Magnetic Yes
Total magnetic moment [μB] 0.351
Spin axis y
Magnetic anisotropy energy, xz [meV/unit cell] 0.029
Magnetic anisotropy energy, yz [meV/unit cell] 0.029
Nearest neighbor exchange coupling [meV] 17.657
Anisotropic exchange (out-of-plane) [meV] -0.009
Single-ion anisotropy (out-of-plane) [meV] 0.000
Maximum value of Sz at magnetic sites 0.500
Number of nearest neighbors 1
Energy above convex hull [eV/atom] 0.555
Heat of formation [eV/atom] -0.250