Overview: Pb₂I₂

Structure info
Layer group	c2/m11
Layer group number	18
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.334
Heat of formation [eV/atom]	-0.186
Dynamically stable	No

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

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	4.221	0.000	0.000	Yes
2	-2.103	3.660	0.000	Yes
3	0.000	0.000	18.856	No

Lengths [Å]	4.221	4.221	18.856
Angles [°]	90.000	90.000	119.879

Crystal structure

Symmetries
2D Bravais type	Centered rectangular (oc)
Layer group number	18
Layer group	c2/m11
Space group number (bulk in AA-stacking)	12
Space group (bulk in AA-stacking)	C2/m
Point group	2/m
Inversion symmetry	Yes

Structure data
Formula	Pb2I2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	15.446
Thickness [Å]	6.947

Stability

Convex hull

I2Pb2 (2IPb-2)
Heat of formation [eV/atom]	-0.19
Energy above convex hull [eV/atom]	0.33

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]

-1.52

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	18.43	8.27	2.63
yy	8.06	20.17	-3.33
xy	2.98	-3.30	16.30

Stiffness tensor eigenvalues
Eigenvalue 0	8.66 N/m
Eigenvalue 1	18.70 N/m
Eigenvalue 2	27.54 N/m

Electronic bands

Band structure and DOS (PBE)

Properties [eV]
Band gap	0.000
Direct band gap	0.000
Vacuum level shift	0.004
Fermi level wrt. vacuum	-4.860

Fermi surface

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	I	-0.39
1	I	-0.39
2	Pb	0.39
3	Pb	0.39

Optical polarizability

Properties
Interband polarizability (x) [Å]	12.973
Interband polarizability (y) [Å]	13.196
Interband polarizability (z) [Å]	0.784
Plasma frequency (x) [eV Å0.5]	5.698
Plasma frequency (y) [eV Å0.5]	6.304

Miscellaneous

Miscellaneous details
Unique ID	2IPb-2
Number of atoms	4
Number of species	2
Formula	Pb2I2
Reduced formula	PbI
Stoichiometry	AB
Unit cell area [Å2]	15.446
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB/IPb/I2Pb2-9c53dfa99cbb
Old uid	I2Pb2-9c53dfa99cbb
Space group (bulk in AA-stacking)	C2/m
Space group number (bulk in AA-stacking)	12
Point group	2/m
Inversion symmetry	Yes
Layer group number	18
Layer group	c2/m11
2D Bravais type	Centered rectangular (oc)
Thickness [Å]	6.947
Structure origin	original03-18
Band gap [eV]	0.000
Direct band gap [eV]	0.000

Miscellaneous details
gap_dir_nosoc	0.000
Vacuum level [eV]	5.106
Fermi level wrt. vacuum [eV]	-4.860
Vacuum level shift [eV]	0.004
Out-of-plane dipole [e Å/unit cell]	0.000
minhessianeig	-1.523
Dynamically stable	No
Interband polarizability (x) [Å]	12.973
Interband polarizability (y) [Å]	13.196
Interband polarizability (z) [Å]	0.784
Plasma frequency (x) [eV Å0.5]	5.698
Plasma frequency (y) [eV Å0.5]	6.304
Energy [eV]	-11.216
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]	0.334
Heat of formation [eV/atom]	-0.186