Overview: BaBr₂

Structure info
Layer group	p-6m2
Layer group number	78
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.167
Heat of formation [eV/atom]	-2.099
Dynamically stable	Yes

Basic properties
Magnetic	No
Out-of-plane dipole [e Å/unit cell]	-0.000
Band gap (PBE) [eV]	4.157
Band gap (HSE) [eV]	5.328
Band gap (G₀W₀) [eV]	7.284

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	4.692	0.000	0.000	Yes
2	-2.346	4.064	0.000	Yes
3	0.000	0.000	18.674	No

Lengths [Å]	4.692	4.692	18.674
Angles [°]	90.000	90.000	120.000

Crystal structure

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	BaBr2
Stoichiometry	AB2
Number of atoms	3
Unit cell area [Å2]	19.068
Thickness [Å]	3.674

Stability

Convex hull

BaBr2 (1BaBr2-2)
Heat of formation [eV/atom]	-2.10
Energy above convex hull [eV/atom]	0.17

Monolayers from C2DB
BaBr2 (1BaBr2-1)	-2.21 eV/atom
Ba2Br4 (2BaBr2-1)	-2.19 eV/atom
BaBr2, (1BaBr2-2)	-2.10 eV/atom
BaBr2 (1BaBr2-3)	-2.02 eV/atom
Ba2Br2 (2BaBr-1)	-1.31 eV/atom

Bulk crystals from OQMD123
Ba4Br8	-2.27 eV/atom
Ba	0.00 eV/atom
Br4	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Deformation potentials

DVB [eV]	xx	yy	xy
Γ	2.81	2.85	0.01
M	2.83	3.13	-0.20
K	3.39	3.44	0.01
kVBM	2.54	2.55	-0.03

	xx	yy	xy
Band gap [eV]	-1.93	0.40	-1.88

DCB [eV]	xx	yy	xy
Γ	-0.67	-0.63	0.01
M	0.61	2.95	-1.91
K	0.03	0.06	0.00
kCBM	0.61	2.95	-1.91

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	17.45	8.94	-0.05
yy	8.97	17.26	-0.02
xy	0.00	0.00	8.70

Stiffness tensor eigenvalues
Eigenvalue 0	8.40 N/m
Eigenvalue 1	8.70 N/m
Eigenvalue 2	26.31 N/m

Piezoelectric tensor

cij [e/Å]	xx	yy	xy
x	0.00	0.00	0.02
y	0.02	-0.03	0.00
z	-0.00	-0.00	0.00

cijclamped [e/Å]	xx	yy	xy
x	0.00	0.00	-0.10
y	-0.10	0.10	0.00
z	0.00	-0.00	0.00

Electronic bands

Band structure and DOS (PBE)

Properties [eV]
Band gap	4.157
Direct band gap	4.211
VBM wrt. vacuum	-7.345
CBM wrt. vacuum	-3.188
Vacuum level shift	-0.000

Band structure (HSE06@PBE)

Properties [eV]
Band gap	5.328
Direct band gap	5.352
VBM wrt. vacuum	-8.190
CBM wrt. vacuum	-2.862

Band structure (G₀W₀@PBE)

Properties [eV]
Band gap	7.284
Direct band gap	7.307
VBM wrt. vacuum	-9.709
CBM wrt. vacuum	-2.426

Effective masses

Property (VBM)	Value
Min eff. mass	6.72 m0
Max eff. mass	7.65 m0
DOS eff. mass	7.17 m0
Crystal coordinates	[0.117, 0.117]
Warping parameter	-0.000
Barrier height	> 3.7 meV
Distance to barrier	> 0.0154 Å-1

Property (CBM)	Value
Min eff. mass	3.05 m0
Max eff. mass	7.54 m0
DOS eff. mass	4.98 m0
Crystal coordinates	[0.422, 0.022]
Warping parameter	0.002
Barrier height	0.5 meV
Distance to barrier	0.00573 Å-1

Electronic properties

Born charges

ZBaij	ux	uy	uz
Px	2.46	0.00	0.00
Py	0.00	2.46	0.00
Pz	0.00	-0.00	0.89

ZBrij	ux	uy	uz
Px	-1.23	0.00	-0.00
Py	0.00	-1.23	0.00
Pz	0.00	-0.00	-0.44

ZBrij	ux	uy	uz
Px	-1.23	0.00	0.00
Py	0.00	-1.23	-0.00
Pz	0.00	0.00	-0.44

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Ba	1.51
1	Br	-0.75
2	Br	-0.76

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	0.943
Interband polarizability (y) [Å]	0.943
Interband polarizability (z) [Å]	0.339
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000

Infrared polarizability

Static polarizability [Å]
Phonons only (x)	1.68
Phonons only (y)	1.68
Phonons only (z)	0.11
Total (phonons + electrons) (x)	2.63
Total (phonons + electrons) (y)	2.63
Total (phonons + electrons) (z)	0.45

Optical absorption (BSE and RPA)

Exciton binding energy (BSE) [eV]

2.24

Second harmonic generation

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

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

Miscellaneous

Miscellaneous details
Unique ID	1BaBr2-2
Number of atoms	3
Number of species	2
Formula	BaBr2
Reduced formula	BaBr2
Stoichiometry	AB2
Unit cell area [Å2]	19.068
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB2/BaBr2/BaBr2-1a59eff92917
Old uid	BaBr2-1a59eff92917
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]	3.674
Structure origin	original03-18
Band gap [eV]	4.157
Direct band gap [eV]	4.211
gap_dir_nosoc	4.271
Vacuum level [eV]	3.017
Fermi level wrt. vacuum [eV]	-5.267
VBM wrt. vacuum [eV]	-7.345
CBM wrt. vacuum [eV]	-3.188
Vacuum level shift [eV]	-0.000
Out-of-plane dipole [e Å/unit cell]	-0.000
minhessianeig	-0.000
Dynamically stable	Yes

Miscellaneous details
Band gap [eV]	5.328
Direct band gap [eV]	5.352
Fermi level wrt. vacuum [eV]	-4.638
VBM wrt. vacuum [eV]	-8.190
CBM wrt. vacuum [eV]	-2.862
Band gap [eV]	7.284
Direct band gap [eV]	7.307
Fermi level wrt. vacuum [eV]	-6.067
VBM wrt. vacuum [eV]	-9.709
CBM wrt. vacuum [eV]	-2.426
E_B	2.239
Interband polarizability (x) [Å]	0.943
Interband polarizability (y) [Å]	0.943
Interband polarizability (z) [Å]	0.339
Static polarizability (phonons) (x) [Å]	1.683
Static polarizability (phonons + electrons) (x) [Å]	2.626
Static polarizability (phonons) (y) [Å]	1.685
Static polarizability (phonons + electrons) (y) [Å]	2.627
Static polarizability (phonons) (z) [Å]	0.110
Static polarizability (phonons + electrons) (z) [Å]	0.449
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000
Energy [eV]	-11.295
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]	0.167
Heat of formation [eV/atom]	-2.099