Overview: PbI₂

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

Stability
Energy above convex hull [eV/atom]	0.078
Heat of formation [eV/atom]	-0.614
Dynamically stable	Yes

Basic properties
Magnetic	No
Out-of-plane dipole [e Å/unit cell]	-0.000
Band gap (PBE) [eV]	1.577
Band gap (HSE) [eV]	2.404
Band gap (G₀W₀) [eV]	3.338

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	4.502	0.000	0.000	Yes
2	-2.251	3.899	0.000	Yes
3	0.000	0.000	19.062	No

Lengths [Å]	4.502	4.502	19.062
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	PbI2
Stoichiometry	AB2
Number of atoms	3
Unit cell area [Å2]	17.556
Thickness [Å]	4.062

Stability

Convex hull

PbI2 (1PbI2-2)
Heat of formation [eV/atom]	-0.61
Energy above convex hull [eV/atom]	0.08

Monolayers from C2DB
PbI2 (1PbI2-1)	-0.69 eV/atom
Pb6I12 (6PbI2-1)	-0.66 eV/atom
Pb2I4 (2PbI2-1)	-0.64 eV/atom
Pb2I4 (2PbI2-2)	-0.62 eV/atom
PbI2, (1PbI2-2)	-0.61 eV/atom
Pb2I4 (2PbI2-3)	-0.60 eV/atom
PbI2 (1PbI2-3)	-0.55 eV/atom
Pb2I2 (2IPb-1)	-0.20 eV/atom
Pb2I2 (2IPb-2)	-0.19 eV/atom

Bulk crystals from OQMD123
Pb4I8	-0.69 eV/atom
I4	0.00 eV/atom
Pb	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Deformation potentials

DVB [eV]	xx	yy	xy
Γ	-2.58	-2.60	0.00
M	1.01	1.02	0.00
K	0.32	0.35	0.01
kVBM	-3.36	-2.41	-0.80

	xx	yy	xy
Band gap [eV]	-0.78	-1.72	0.80

DCB [eV]	xx	yy	xy
Γ	-4.14	-4.13	0.00
M	0.02	-1.36	1.12
K	1.48	1.56	0.02
kCBM	-4.14	-4.13	0.00

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	16.36	9.27	-0.07
yy	9.48	16.12	-0.07
xy	0.00	0.00	7.04

Stiffness tensor eigenvalues
Eigenvalue 0	6.87 N/m
Eigenvalue 1	7.04 N/m
Eigenvalue 2	25.61 N/m

Piezoelectric tensor

cij [e/Å]	xx	yy	xy
x	0.00	0.00	-0.23
y	-0.20	0.20	-0.00
z	0.00	-0.00	0.00

cijclamped [e/Å]	xx	yy	xy
x	0.00	0.00	-0.23
y	-0.23	0.23	-0.00
z	-0.00	0.00	0.00

Electronic bands

Band structure and DOS (PBE)

Properties [eV]
Band gap	1.577
Direct band gap	1.628
VBM wrt. vacuum	-6.240
CBM wrt. vacuum	-4.663
Vacuum level shift	-0.000

Band structure (HSE06@PBE)

Properties [eV]
Band gap	2.404
Direct band gap	2.543
VBM wrt. vacuum	-6.737
CBM wrt. vacuum	-4.333

Band structure (G₀W₀@PBE)

Properties [eV]
Band gap	3.338
Direct band gap	3.367
VBM wrt. vacuum	-7.485
CBM wrt. vacuum	-4.147

Effective masses

Property (VBM)	Value
Min eff. mass	0.38 m0
Max eff. mass	1.19 m0
DOS eff. mass	0.67 m0
Crystal coordinates	[0.120, 0.120]
Warping parameter	-0.000
Barrier height	> 47.6 meV
Distance to barrier	> 0.0216 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	[0.000, 0.000]
Warping parameter	0.003
Barrier height	> 120.0 meV
Distance to barrier	> 0.0214 Å-1

Electronic properties

Born charges

ZPbij	ux	uy	uz
Px	3.27	-0.00	0.00
Py	-0.00	3.27	-0.00
Pz	-0.00	0.00	0.63

ZIij	ux	uy	uz
Px	-1.63	0.00	0.00
Py	0.00	-1.63	-0.00
Pz	0.00	-0.00	-0.32

ZIij	ux	uy	uz
Px	-1.63	-0.00	-0.00
Py	0.00	-1.63	0.00
Pz	0.00	0.00	-0.32

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Pb	0.92
1	I	-0.46
2	I	-0.46

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	2.598
Interband polarizability (y) [Å]	2.598
Interband polarizability (z) [Å]	0.461
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000

Infrared polarizability

Static polarizability [Å]
Phonons only (x)	5.27
Phonons only (y)	5.26
Phonons only (z)	0.05
Total (phonons + electrons) (x)	7.87
Total (phonons + electrons) (y)	7.86
Total (phonons + electrons) (z)	0.51

Optical absorption (BSE and RPA)

Exciton binding energy (BSE) [eV]

0.76

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	1PbI2-2
Number of atoms	3
Number of species	2
Formula	PbI2
Reduced formula	PbI2
Stoichiometry	AB2
Unit cell area [Å2]	17.556
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB2/PbI2/PbI2-9e6494406d07
Old uid	PbI2-9e6494406d07
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]	4.062
Structure origin	original03-18
Band gap [eV]	1.577
Direct band gap [eV]	1.628
gap_dir_nosoc	2.904
Vacuum level [eV]	3.352
Fermi level wrt. vacuum [eV]	-5.452
VBM wrt. vacuum [eV]	-6.240
CBM wrt. vacuum [eV]	-4.663
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]	2.404
Direct band gap [eV]	2.543
Fermi level wrt. vacuum [eV]	-5.380
VBM wrt. vacuum [eV]	-6.737
CBM wrt. vacuum [eV]	-4.333
Band gap [eV]	3.338
Direct band gap [eV]	3.367
Fermi level wrt. vacuum [eV]	-5.260
VBM wrt. vacuum [eV]	-7.485
CBM wrt. vacuum [eV]	-4.147
E_B	0.762
Interband polarizability (x) [Å]	2.598
Interband polarizability (y) [Å]	2.598
Interband polarizability (z) [Å]	0.461
Static polarizability (phonons) (x) [Å]	5.273
Static polarizability (phonons + electrons) (x) [Å]	7.871
Static polarizability (phonons) (y) [Å]	5.264
Static polarizability (phonons + electrons) (y) [Å]	7.862
Static polarizability (phonons) (z) [Å]	0.053
Static polarizability (phonons + electrons) (z) [Å]	0.514
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000
Energy [eV]	-8.559
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]	0.078
Heat of formation [eV/atom]	-0.614