Structure info
Layer group p4/mmm
Layer group number 61
Structure origin original03-18
Stability
Energy above convex hull [eV/atom] 0.345
Heat of formation [eV/atom] -0.460
Dynamically stable No
Basic properties
Magnetic No
Band gap (PBE) [eV] 0.000
XYZ CIF JSON
Axis x [Å] y [Å] z [Å] Periodic
1 3.895 0.000 0.000 Yes
2 0.000 3.897 0.000 Yes
3 0.000 0.000 17.827 No
Lengths [Å] 3.895 3.897 17.827
Angles [°] 90.000 90.000 90.000

Symmetries
2D Bravais type Square (tp)
Layer group number 61
Layer group p4/mmm
Space group number (bulk in AA-stacking) 123
Space group (bulk in AA-stacking) P4/mmm
Point group 4/mmm
Inversion symmetry Yes
Structure data
Formula Nb2Se2
Stoichiometry AB
Number of atoms 4
Unit cell area [Å2] 15.181
Thickness [Å] 3.709

Nb2Se2 (2NbSe-3)
Heat of formation [eV/atom] -0.46
Energy above convex hull [eV/atom] 0.34
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/3/phonon_bs.png
Minimum eigenvalue of Hessian [eV/Ų] -2.41

Cij (N/m) xx yy xy
xx 67.15 47.94 -0.00
yy 47.69 67.52 -0.00
xy 0.00 0.00 98.23
Stiffness tensor eigenvalues
Eigenvalue 0 19.52 N/m
Eigenvalue 1 98.23 N/m
Eigenvalue 2 115.14 N/m

Key values [eV]
Band gap (PBE) 0.000
Direct band gap (PBE) 0.000
Fermi level wrt. vacuum (PBE) -4.882
DOS BZ

AB/2NbSe/3/fermi_surface.png

Atom No. Chemical symbol Charges [|e|]
0 Nb 0.79
1 Se -0.79
2 Nb 0.79
3 Se -0.79

AB/2NbSe/3/rpa-pol-x.png AB/2NbSe/3/rpa-pol-z.png
AB/2NbSe/3/rpa-pol-y.png
Properties
Interband polarizability (x) [Å] 19.295
Interband polarizability (y) [Å] 18.319
Interband polarizability (z) [Å] 0.477
Plasma frequency (x) [eV Å0.5] 10.908
Plasma frequency (y) [eV Å0.5] 10.942

Miscellaneous details
Unique ID 2NbSe-3
Number of atoms 4
Number of species 2
Formula Nb2Se2
Reduced formula NbSe
Stoichiometry AB
Unit cell area [Å2] 15.181
Original file-system folder /home/niflheim2/cmr/C2DB-ASR/tree/AB/NbSe/Nb2Se2-c9e9c08ae72e
Old uid Nb2Se2-c9e9c08ae72e
Space group (bulk in AA-stacking) P4/mmm
Space group number (bulk in AA-stacking) 123
Point group 4/mmm
Inversion symmetry Yes
Layer group number 61
Layer group p4/mmm
2D Bravais type Square (tp)
Thickness [Å] 3.709
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] 4.162
Fermi level wrt. vacuum (PBE) [eV] -4.882
minhessianeig -2.405
Dynamically stable No
Interband polarizability (x) [Å] 19.295
Interband polarizability (y) [Å] 18.319
Interband polarizability (z) [Å] 0.477
Plasma frequency (x) [eV Å0.5] 10.908
Plasma frequency (y) [eV Å0.5] 10.942
Energy [eV] -29.458
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] 0.345
Heat of formation [eV/atom] -0.460