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Structure info
Layer group p-6m2
Layer group number 78
Structure origin original03-18
Stability
Energy above convex hull [eV/atom] 0.000
Heat of formation [eV/atom] -0.717
Dynamically stable Yes
Basic properties
Magnetic No
Band gap (PBE) [eV] 1.997
Band gap (HSE06) [eV] 2.721
Band gap (G₀W₀) [eV] 3.537
XYZ CIF JSON
Axis x [Å] y [Å] z [Å] Periodic
1 3.778 -0.000 0.000 Yes
2 -1.889 3.272 0.000 Yes
3 -0.000 0.000 19.913 No
Lengths [Å] 3.778 3.778 19.913
Angles [°] 90.000 90.000 120.000

Symmetries
2D Bravais type Hexagonal (hp)
Layer group number 78
Layer group p-6m2
Space group number (bulk in AA-stacking) 187
Space group (bulk in AA-stacking) P-6m2
Point group -6m2
Inversion symmetry No
Structure data
Formula Al2Se2
Stoichiometry AB
Number of atoms 4
Unit cell area [Å2] 12.359
Thickness [Å] 4.923

Al2Se2 (2AlSe-1)
Heat of formation [eV/atom] -0.72
Energy above convex hull [eV/atom] 0.00
Monolayers from C2DB
Al8Se12 (4Al2Se3-1) -0.86 eV/atom
Al4Se6 (2Al2Se3-1) -0.84 eV/atom
Al4Se6 (2Al2Se3-2) -0.83 eV/atom
Al4Se6 (2Al2Se3-3) -0.81 eV/atom
Al2Se3 (1Al2Se3-1) -0.79 eV/atom
Al6Se9 (3Al2Se3-1) -0.77 eV/atom
Al2Se3 (1Al2Se3-2) -0.77 eV/atom
Al3Se4 (1Al3Se4-1) -0.72 eV/atom
Al2Se2, (2AlSe-1) -0.72 eV/atom
Al2Se2 (2AlSe-2) -0.71 eV/atom
Al2Se2 (2AlSe-3) -0.69 eV/atom
Al2Se5 (1Al2Se5-1) -0.60 eV/atom
Al2Se4 (2AlSe2-1) -0.55 eV/atom
AlSe2 (1AlSe2-1) -0.55 eV/atom
Al2Se2 (2AlSe-4) -0.36 eV/atom
Al2Se4 (2AlSe2-2) -0.31 eV/atom
Al2Se2 (2AlSe-5) -0.14 eV/atom
AlSe4 (1AlSe4-1) -0.13 eV/atom
Se2 (2Se-1) 0.21 eV/atom
Se2 (2Se-2) 0.29 eV/atom
Bulk crystals from OQMD123
Al4Se6 -0.84 eV/atom
Al 0.00 eV/atom
Se3 0.00 eV/atom

AB/2AlSe/1/phonon_bs.png
Minimum eigenvalue of Hessian [eV/Ų] -0.00

DVB [eV] xx yy xy
Γ 2.41 2.31 -0.00
M -0.04 1.91 -1.69
K -0.01 -0.13 -0.00
kVBM 2.56 1.83 -0.32
xx yy xy
Band gap [eV] -0.91 -4.69 4.12
DCB [eV] xx yy xy
Γ -9.09 -9.07 -0.00
M 1.65 -2.85 3.80
K 2.60 2.47 -0.00
kCBM 1.65 -2.85 3.80

Cij (N/m) xx yy xy
xx 71.84 19.36 -0.00
yy 18.80 72.63 -0.00
xy 0.00 0.00 54.56
Stiffness tensor eigenvalues
Eigenvalue 0 53.15 N/m
Eigenvalue 1 54.56 N/m
Eigenvalue 2 91.31 N/m

cij [e/Å] xx yy xy
x -0.00 -0.00 -0.06
y -0.04 0.04 0.00
z 0.00 -0.00 0.00
cijclamped [e/Å] xx yy xy
x -0.00 -0.00 -0.29
y -0.29 0.29 0.00
z 0.00 0.00 0.00

Key values [eV]
Band gap (PBE) 1.997
Direct band gap (PBE) 2.645
Valence band maximum wrt. vacuum (PBE) -5.826
Conduction band minimum wrt. vacuum (PBE) -3.828
DOS BZ

Key values [eV]
Band gap (HSE06) 2.721
Direct band gap (HSE06) 3.435
Valence band maximum wrt. vacuum (HSE06) -6.313
Conduction band minimum wrt. vacuum (HSE06) -3.593

Key values [eV]
Band gap (G₀W₀) 3.537
Direct band gap (G₀W₀) 4.206
Valence band maximum wrt. vacuum (G₀W₀) -7.032
Conduction band minimum wrt. vacuum (G₀W₀) -3.495

VBM
Property (VBM) Value
Min eff. mass 1.87 m0
Max eff. mass 5.11 m0
DOS eff. mass 3.09 m0
Crystal coordinates [0.113, 0.113]
Warping parameter -0.000
Barrier height > 12.6 meV
Distance to barrier > 0.0255 Å-1
CBM
Property (CBM) Value
Min eff. mass 0.29 m0
Max eff. mass 1.50 m0
DOS eff. mass 0.73 m0
Crystal coordinates [0.499, 0.001]
Warping parameter 0.004
Barrier height > 72.8 meV
Distance to barrier > 0.0255 Å-1

ZAlij ux uy uz
Px 2.11 -0.00 -0.00
Py 0.00 2.11 0.00
Pz -0.00 -0.00 0.27
ZSeij ux uy uz
Px -2.11 0.00 0.00
Py -0.00 -2.11 -0.00
Pz -0.00 0.00 -0.27
ZAlij ux uy uz
Px 2.11 -0.00 0.00
Py 0.00 2.11 -0.00
Pz 0.00 0.00 0.27
ZSeij ux uy uz
Px -2.11 0.00 -0.00
Py -0.00 -2.11 0.00
Pz 0.00 -0.00 -0.27

Atom No. Chemical symbol Charges [|e|]
0 Al 1.38
1 Al 1.43
2 Se -1.40
3 Se -1.40

AB/2AlSe/1/rpa-pol-x.png AB/2AlSe/1/rpa-pol-z.png
AB/2AlSe/1/rpa-pol-y.png
Properties
Interband polarizability (x) [Å] 3.631
Interband polarizability (y) [Å] 3.631
Interband polarizability (z) [Å] 0.517
Plasma frequency (x) [eV Å0.5] 0.000
Plasma frequency (y) [eV Å0.5] 0.000

AB/2AlSe/1/ir-pol-x.png AB/2AlSe/1/ir-pol-z.png
AB/2AlSe/1/ir-pol-y.png
Static polarizability [Å]
Phonons only (x) 1.74
Phonons only (y) 1.74
Phonons only (z) 0.02
Total (phonons + electrons) (x) 5.37
Total (phonons + electrons) (y) 5.37
Total (phonons + electrons) (z) 0.54

AB/2AlSe/1/absx.png
Exciton binding energy (BSE) [eV] 1.10
AB/2AlSe/1/absz.png

AB/2AlSe/1/shg1.png
Element Relations
yyy yyy=-xxy=-yxx=-xyx
Others 0=xxx=xxz=xyy=xyz=xzx=xzy=xzz=yxy=yxz=yyx=yyz=yzx= yzy=yzz=zxx=zxy=zxz=zyx=zyy=zyz=zzx=zzy=zzz
AB/2AlSe/1/shg2.png

Shift-current
Element Relations
yyy yyy=-xyx=-yxx=-xxy
Others 0=xxx=xxz=xyy=xyz=xzx=xzy=xzz=yxy=yxz=yyx=yyz=yzx= yzy=yzz=zxx=zxy=zxz=zyx=zyy=zyz=zzx=zzy=zzz

AB/2AlSe/1/Raman.png
Mode Frequency (1/cm) Degeneracy
Mode 1 0. 3
Mode 2 59.2 2
Mode 3 125.4 1
Mode 4 294.6 4
Mode 5 329.2 1
Mode 6 458.2 1

Miscellaneous details
Unique ID 2AlSe-1
Number of atoms 4
Number of species 2
Formula Al2Se2
Reduced formula AlSe
Stoichiometry AB
Unit cell area [Å2] 12.359
Original file-system folder /home/niflheim2/cmr/C2DB-ASR/tree/AB/AlSe/Al2Se2-129a514b51ad
Old uid Al2Se2-129a514b51ad
Space group (bulk in AA-stacking) P-6m2
Space group number (bulk in AA-stacking) 187
Point group -6m2
Inversion symmetry No
Layer group number 78
Layer group p-6m2
2D Bravais type Hexagonal (hp)
Thickness [Å] 4.923
Structure origin original03-18
Band gap (PBE) [eV] 1.997
Direct band gap (PBE) [eV] 2.645
gap_dir_nosoc 2.651
Vacuum level [eV] 3.820
Fermi level wrt. vacuum (PBE) [eV] -4.827
Valence band maximum wrt. vacuum (PBE) [eV] -5.826
Conduction band minimum wrt. vacuum (PBE) [eV] -3.828
minhessianeig -0.000
Dynamically stable Yes
Band gap (HSE06) [eV] 2.721
Miscellaneous details
Direct band gap (HSE06) [eV] 3.435
Fermi level wrt. vacuum (HSE) [eV] -4.637
Valence band maximum wrt. vacuum (HSE06) [eV] -6.313
Conduction band minimum wrt. vacuum (HSE06) [eV] -3.593
Band gap (G₀W₀) [eV] 3.537
Direct band gap (G₀W₀) [eV] 4.206
Fermi level wrt. vacuum (G₀W₀) [eV] -5.264
Valence band maximum wrt. vacuum (G₀W₀) [eV] -7.032
Conduction band minimum wrt. vacuum (G₀W₀) [eV] -3.495
E_B 1.096
Interband polarizability (x) [Å] 3.631
Interband polarizability (y) [Å] 3.631
Interband polarizability (z) [Å] 0.517
Static polarizability (phonons) (x) [Å] 1.738
Static polarizability (phonons + electrons) (x) [Å] 5.368
Static polarizability (phonons) (y) [Å] 1.737
Static polarizability (phonons + electrons) (y) [Å] 5.368
Static polarizability (phonons) (z) [Å] 0.021
Static polarizability (phonons + electrons) (z) [Å] 0.538
Plasma frequency (x) [eV Å0.5] 0.000
Plasma frequency (y) [eV Å0.5] 0.000
Energy [eV] -17.311
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] 0.000
Heat of formation [eV/atom] -0.717