Atoms: Ga₂Se₂

Structure info
Layer group	p-6m2
Layer group number	78
Structure origin	exfoliated02-21
COD id of parent bulk structure	COD 1530863

Stability
Energy above convex hull [eV/atom]	0.432
Heat of formation [eV/atom]	-0.169
Dynamically stable	Yes

Basic properties
Magnetic state	NM
Band gap [eV]	0.697
Band gap (HSE06) [eV]	0.809

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	3.953	-0.000	0.000	Yes
2	-1.977	3.423	0.000	Yes
3	-0.000	0.000	34.776	No

Lengths [Å]	3.953	3.953	34.776
Angles [°]	90.000	90.000	120.000

Convex hull

Ga2Se2 (2GaSe-7)
Heat of formation [eV/atom]	-0.17
Energy above convex hull [eV/atom]	0.43

Monolayers from C2DB
Ga2Se2, (2GaSe-1)	-0.60 eV/atom
Ga2Se2, (2GaSe-2)	-0.60 eV/atom
Ga8Se12, (4Ga2Se3-1)	-0.59 eV/atom
Ga2Se2, (2GaSe-3)	-0.55 eV/atom
Ga2Se3, (1Ga2Se3-1)	-0.53 eV/atom
Se12Ga13, (1Se12Ga13-1)	-0.53 eV/atom
Ga4Se6, (2Ga2Se3-1)	-0.53 eV/atom
Ga4Se6, (2Ga2Se3-2)	-0.52 eV/atom
Ga3Se4, (1Ga3Se4-1)	-0.47 eV/atom
Se12Ga14, (2Se6Ga7-1)	-0.47 eV/atom
Ga2Se3, (1Ga2Se3-2)	-0.45 eV/atom
Se12Ga15, (3Se4Ga5-1)	-0.45 eV/atom
Ga2Se5, (1Ga2Se5-1)	-0.42 eV/atom
Ga2Se2, (2GaSe-4)	-0.37 eV/atom
GaSe2, (1GaSe2-1)	-0.34 eV/atom
Ga2Se2, (2GaSe-5)	-0.30 eV/atom
Ga2Se4, (2GaSe2-1)	-0.24 eV/atom
Ga2Se4, (2GaSe2-2)	-0.23 eV/atom
Ga2Se2, (2GaSe-6)	-0.19 eV/atom
Ga2Se2, (2GaSe-7)	-0.17 eV/atom
Ga2Se4, (2GaSe2-3)	-0.03 eV/atom
GaSe4, (1GaSe4-1)	-0.02 eV/atom
Ga4, (4Ga-1)	0.16 eV/atom
Se2, (2Se-1)	0.21 eV/atom
Se2, (2Se-2)	0.29 eV/atom

Bulk crystals from OQMD123
Ga4Se4	-0.60 eV/atom
Ga4Se6	-0.59 eV/atom
Ga4	0.00 eV/atom
Se3	0.00 eV/atom

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	35.60	9.15	0.01
yy	8.70	36.74	0.01
xy	-0.00	0.00	27.17

Stiffness tensor eigenvalues
Eigenvalue 0	27.17 N/m
Eigenvalue 1	27.23 N/m
Eigenvalue 2	45.10 N/m

Phonons

Property	Value
Minimum eigenvalue of Hessian [eV/Ų]	-0.00

Deformation potentials

DVB (eV)	xx	yy	xy
Γ	-2.34	-2.06	0.08
M	1.22	1.15	0.13
K	2.19	2.21	0.07
kVBM	1.14	1.05	0.14

	xx	yy	xy
Band Gap	-0.19	-0.15	-0.09

DCB (eV)	xx	yy	xy
Γ	-2.61	-2.39	0.07
M	1.37	2.36	-0.85
K	0.95	0.89	0.06
kCBM	0.95	0.89	0.06

Band structure and DOS

Effective masses

Property (VBM)	Value
Min eff. mass	1.36 m0
Max eff. mass	2.05 m0
DOS eff. mass	1.67 m0
Crystal coordinates	[0.157, 0.157]
Warping parameter	-0.000
Barrier height	> 21.3 meV
Distance to barrier	> 0.0184 Å-1

Property (CBM)	Value
Min eff. mass	0.40 m0
Max eff. mass	0.40 m0
DOS eff. mass	0.40 m0
Crystal coordinates	[-0.667, 0.333]
Warping parameter	0.000
Barrier height	> 81.6 meV
Distance to barrier	> 0.0183 Å-1

Electronic band structure (HSE06@PBE)

Property	Value
KVP: Band gap (HSE06) [eV]	0.81
KVP: Direct band gap (HSE06) [eV]	0.83
Valence band maximum wrt. vacuum level (HSE06)	-5.31 eV
Conduction band minimum wrt. vacuum level (HSE06)	-4.50 eV

Born charges

ZGaij	ux	uy	uz
Px	2.75	-0.00	0.00
Py	-0.00	2.75	-0.00
Pz	-0.00	-0.00	-0.01

ZSeij	ux	uy	uz
Px	-2.75	0.00	0.01
Py	0.00	-2.75	-0.00
Pz	-0.00	-0.00	0.01

ZGaij	ux	uy	uz
Px	2.75	-0.00	-0.00
Py	-0.00	2.75	0.00
Pz	0.00	0.00	-0.01

ZSeij	ux	uy	uz
Px	-2.75	0.00	-0.01
Py	0.00	-2.75	0.00
Pz	0.00	0.00	0.01

Optical polarizability

Properties
Static interband polarizability at (x) [Å]	5.975
Static interband polarizability at (y) [Å]	6.463
Static interband polarizability at (z) [Å]	0.615

Infrared polarizability

Static polarizability	[Å]
Phonons only (x)	4.31
Phonons only (y)	4.31
Phonons only (z)	0.00
Total (phonons + electrons) (x)	10.28
Total (phonons + electrons) (y)	10.77
Total (phonons + electrons) (z)	0.62

Bader charges

#	Chemical symbol	Charges [|e|]
0	Ga	0.55
1	Ga	0.55
2	Se	-0.57
3	Se	-0.53

Piezoelectric tensor

cij (e/Ådim-1)	xx	yy	xy
x	-0.00	-0.00	0.08
y	0.07	-0.10	-0.00
z	0.00	0.00	0.00

cclampedij (e/Ådim-1)	xx	yy	xy
x	0.00	0.00	0.36
y	0.36	-0.36	0.00
z	0.00	-0.00	-0.00

Shift current

Element	Relations
xyx	xyx=yxx=xxy
yyy
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

Miscellaneous

Miscellaneous details
Unique ID	2GaSe-7
Number of atoms	4
Number of species	2
Formula	Ga2Se2
Reduced formula	GaSe
Stoichiometry	AB
Unit cell area [Å2]	13.533
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/ICSD-COD/2el/Ga4Se4_2
Old uid	Ga2Se2-cf97a249e884
Inversion symmetry	No
Layer group	p-6m2
Layer group number	78
Structure origin	exfoliated02-21
Band gap [eV]	0.697
gap_dir	0.773
gap_dir_nosoc	0.863
Vacuum level [eV]	1.908
Fermi level [eV]	-2.804
minhessianeig	-0.000
Dynamically stable	Yes
Band gap (HSE06) [eV]	0.809

Miscellaneous details
gap_dir_hse	0.828
vbm_hse	-3.400
cbm_hse	-2.591
Static interband polarizability at (x) [Å]	5.975
Static interband polarizability at (y) [Å]	6.463
Static interband polarizability at (z) [Å]	0.615
Static polarizability (phonons) (x) [Å]	4.306
Static polarizability (phonons + electrons) (x) [Å]	10.281
Static polarizability (phonons) (y) [Å]	4.306
Static polarizability (phonons + electrons) (y) [Å]	10.769
Static polarizability (phonons) (z) [Å]	0.000
Static polarizability (phonons + electrons) (z) [Å]	0.615
Energy [eV]	-13.447
COD id of parent bulk structure	COD 1530863
Magnetic state	NM
Total magnetic moment [μB]	0.000
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]	0.432
Heat of formation [eV/atom]	-0.169