Overview: Cu₂I₂

Structure info
Layer group	p4/nmm
Layer group number	64
Structure origin	original03-18
COD id of parent bulk structure	COD 9013924

Stability
Energy above convex hull [eV/atom]	0.008
Heat of formation [eV/atom]	-0.158
Dynamically stable	No

Basic properties
Magnetic	No
Band gap (PBE) [eV]	1.865
Band gap (HSE06) [eV]	3.552
Band gap (G₀W₀) [eV]	3.504

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	4.115	-0.000	0.000	Yes
2	0.000	4.115	0.000	Yes
3	-0.000	0.000	18.833	No

Lengths [Å]	4.115	4.115	18.833
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Square (tp)
Layer group number	64
Layer group	p4/nmm
Space group number (bulk in AA-stacking)	129
Space group (bulk in AA-stacking)	P4/nmm
Point group	4/mmm
Inversion symmetry	Yes

Structure data
Formula	I2Cu2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	16.933
Thickness [Å]	3.441

Stability

Convex hull

Cu2I2 (2CuI-2)
Heat of formation [eV/atom]	-0.16
Energy above convex hull [eV/atom]	0.01

Monolayers from C2DB
Cu2I2 (2CuI-1)	-0.17 eV/atom
Cu2I2, (2CuI-2)	-0.16 eV/atom
Cu3I3 (3CuI-1)	-0.15 eV/atom
Cu5I5 (5CuI-1)	-0.14 eV/atom
Cu6I6 (6CuI-1)	-0.14 eV/atom
Cu4I4 (4CuI-1)	-0.13 eV/atom
CuI2 (1CuI2-1)	-0.13 eV/atom
Cu2I3 (1Cu2I3-1)	-0.12 eV/atom
Cu4I6 (2Cu2I3-1)	-0.12 eV/atom
Cu3I6 (3CuI2-1)	-0.11 eV/atom
Cu9I11 (1Cu9I11-1)	-0.10 eV/atom
Cu6I6 (6CuI-2)	-0.10 eV/atom
Cu3I3 (3CuI-2)	-0.10 eV/atom
Cu6I6 (6CuI-3)	-0.10 eV/atom
Cu3I3 (3CuI-3)	-0.10 eV/atom
Cu3I3 (3CuI-4)	-0.09 eV/atom
Cu2I4 (2CuI2-1)	-0.09 eV/atom
Cu3I5 (1Cu3I5-1)	-0.09 eV/atom
Cu4I4 (4CuI-2)	-0.09 eV/atom
CuI (1CuI-1)	-0.08 eV/atom
Cu4I8 (4CuI2-1)	-0.08 eV/atom
Cu4I8 (4CuI2-2)	-0.08 eV/atom
Cu3I4 (1Cu3I4-1)	-0.07 eV/atom
Cu2I4 (2CuI2-2)	-0.06 eV/atom
Cu4I6 (2Cu2I3-2)	-0.05 eV/atom
CuI2 (1CuI2-2)	-0.05 eV/atom
Cu2I5 (1Cu2I5-1)	-0.03 eV/atom
Cu2I6 (2CuI3-1)	0.05 eV/atom
CuI2 (1CuI2-3)	0.09 eV/atom
Cu2I6 (2CuI3-2)	0.10 eV/atom

Bulk crystals from OQMD123
CuI	-0.16 eV/atom
Cu	0.00 eV/atom
I4	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.19

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	32.66	-0.79	-0.00
yy	-1.59	32.91	-0.00
xy	0.00	0.00	-3.28

Stiffness tensor eigenvalues
Eigenvalue 0	-3.28 N/m
Eigenvalue 1	31.66 N/m
Eigenvalue 2	33.91 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	1.865
Direct band gap (PBE)	1.865
Valence band maximum wrt. vacuum (PBE)	-4.570
Conduction band minimum wrt. vacuum (PBE)	-2.705

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	3.552
Direct band gap (HSE06)	3.552
Valence band maximum wrt. vacuum (HSE06)	-5.924
Conduction band minimum wrt. vacuum (HSE06)	-2.372

Electronic band structure (G₀W₀@PBE)

Key values [eV]
Band gap (G₀W₀)	3.504
Direct band gap (G₀W₀)	3.504
Valence band maximum wrt. vacuum (G₀W₀)	-5.626
Conduction band minimum wrt. vacuum (G₀W₀)	-2.122

Effective masses

Property (VBM)	Value
Min eff. mass	0.58 m0
Max eff. mass	0.59 m0
DOS eff. mass	0.58 m0
Crystal coordinates	[0.000, -0.000]
Warping parameter	-0.008
Barrier height	> 47.6 meV
Distance to barrier	> 0.0152 Å-1

Property (CBM)	Value
Min eff. mass	0.30 m0
Max eff. mass	0.31 m0
DOS eff. mass	0.30 m0
Crystal coordinates	[-0.000, 0.000]
Warping parameter	0.003
Barrier height	> 93.3 meV
Distance to barrier	> 0.0152 Å-1

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	I	-0.32
1	I	-0.32
2	Cu	0.32
3	Cu	0.32

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	2.253
Interband polarizability (y) [Å]	2.253
Interband polarizability (z) [Å]	0.421
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000

Optical absorption (BSE and RPA)

Exciton binding energy (BSE) [eV]

0.92

Miscellaneous

Miscellaneous details
Unique ID	2CuI-2
Number of atoms	4
Number of species	2
Formula	I2Cu2
Reduced formula	ICu
Stoichiometry	AB
Unit cell area [Å2]	16.933
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB/CuI/Cu2I2-48470661aab1
Old uid	Cu2I2-48470661aab1
Space group (bulk in AA-stacking)	P4/nmm
Space group number (bulk in AA-stacking)	129
Point group	4/mmm
Inversion symmetry	Yes
Layer group number	64
Layer group	p4/nmm
2D Bravais type	Square (tp)
Thickness [Å]	3.441
Structure origin	original03-18
Band gap (PBE) [eV]	1.865
Direct band gap (PBE) [eV]	1.865
gap_dir_nosoc	2.077
Vacuum level [eV]	3.114
Fermi level wrt. vacuum (PBE) [eV]	-3.637
Valence band maximum wrt. vacuum (PBE) [eV]	-4.570
Conduction band minimum wrt. vacuum (PBE) [eV]	-2.705
minhessianeig	-0.192

Miscellaneous details
Dynamically stable	No
Band gap (HSE06) [eV]	3.552
Direct band gap (HSE06) [eV]	3.552
Fermi level wrt. vacuum (HSE) [eV]	-4.148
Valence band maximum wrt. vacuum (HSE06) [eV]	-5.924
Conduction band minimum wrt. vacuum (HSE06) [eV]	-2.372
Band gap (G₀W₀) [eV]	3.504
Direct band gap (G₀W₀) [eV]	3.504
Fermi level wrt. vacuum (G₀W₀) [eV]	-3.874
Valence band maximum wrt. vacuum (G₀W₀) [eV]	-5.626
Conduction band minimum wrt. vacuum (G₀W₀) [eV]	-2.122
E_B	0.916
Interband polarizability (x) [Å]	2.253
Interband polarizability (y) [Å]	2.253
Interband polarizability (z) [Å]	0.421
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000
Energy [eV]	-10.940
COD id of parent bulk structure	COD 9013924
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]	0.008
Heat of formation [eV/atom]	-0.158