Overview: C₂

Structure info
Layer group	p6/mmm
Layer group number	80
Structure origin	original03-18
COD id of parent bulk structure	COD 9012705
ICSD id of parent bulk structure	ICSD 96620
Mono/few-layer report(s)	10.1126/science.1102896

Stability
Energy above convex hull [eV/atom]	0.000
Heat of formation [eV/atom]	-0.007
Dynamically stable	Yes

Basic properties
Magnetic	No
Topology	Z2=1,C_M=1
Band gap (PBE) [eV]	0.000
Band gap (HSE06) [eV]	0.000

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	2.467	-0.000	0.000	Yes
2	-1.234	2.137	0.000	Yes
3	0.000	0.000	15.000	No

Lengths [Å]	2.467	2.467	15.000
Angles [°]	90.000	90.000	120.000

Crystal structure

Symmetries
2D Bravais type	Hexagonal (hp)
Layer group number	80
Layer group	p6/mmm
Space group number (bulk in AA-stacking)	191
Space group (bulk in AA-stacking)	P6/mmm
Point group	6/mmm
Inversion symmetry	Yes

Structure data
Formula	C2
Stoichiometry	A
Number of atoms	2
Unit cell area [Å2]	5.272
Thickness [Å]	0.000

Stability

Convex hull

C2 (2C-1)
Heat of formation [eV/atom]	-0.01
Energy above convex hull [eV/atom]	0.00

Monolayers from C2DB
C2, (2C-1)	-0.01 eV/atom
C14 (14C-1)	0.74 eV/atom

Bulk crystals from OQMD123
C4	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	345.65	70.61	0.00
yy	70.57	345.58	0.00
xy	-0.00	-0.00	275.09

Stiffness tensor eigenvalues
Eigenvalue 0	275.03 N/m
Eigenvalue 1	275.09 N/m
Eigenvalue 2	416.20 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.000
Direct band gap (PBE)	0.000
Valence band maximum wrt. vacuum (PBE)	-4.249
Conduction band minimum wrt. vacuum (PBE)	-4.248

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	0.000
Direct band gap (HSE06)	0.000
Valence band maximum wrt. vacuum (HSE06)	-4.213
Conduction band minimum wrt. vacuum (HSE06)	-4.213

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	C	0.05
1	C	-0.05

Berry phase spectrum

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	6.575
Interband polarizability (y) [Å]	6.575
Interband polarizability (z) [Å]	0.153
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000

Optical absorption (BSE and RPA)

Raman spectrum

Mode	Frequency (1/cm)	Degeneracy
Mode 1	0.	3
Mode 2	847.7	1
Mode 3	1611.6	2

Miscellaneous

Miscellaneous details
Unique ID	2C-1
Number of atoms	2
Number of species	1
Formula	C2
Reduced formula	C
Stoichiometry	A
Unit cell area [Å2]	5.272
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/A/C/C2-a6735a4a3797
Old uid	C2-a6735a4a3797
Space group (bulk in AA-stacking)	P6/mmm
Space group number (bulk in AA-stacking)	191
Point group	6/mmm
Inversion symmetry	Yes
Layer group number	80
Layer group	p6/mmm
2D Bravais type	Hexagonal (hp)
Thickness [Å]	0.000
Structure origin	original03-18
Band gap (PBE) [eV]	0.000
Direct band gap (PBE) [eV]	0.000
gap_dir_nosoc	0.000
Vacuum level [eV]	2.336
Fermi level wrt. vacuum (PBE) [eV]	-4.248
Valence band maximum wrt. vacuum (PBE) [eV]	-4.249

Miscellaneous details
Conduction band minimum wrt. vacuum (PBE) [eV]	-4.248
minhessianeig	-0.000
Dynamically stable	Yes
Band gap (HSE06) [eV]	0.000
Direct band gap (HSE06) [eV]	0.000
Fermi level wrt. vacuum (HSE) [eV]	-4.213
Valence band maximum wrt. vacuum (HSE06) [eV]	-4.213
Conduction band minimum wrt. vacuum (HSE06) [eV]	-4.213
Interband polarizability (x) [Å]	6.575
Interband polarizability (y) [Å]	6.575
Interband polarizability (z) [Å]	0.153
Plasma frequency (x) [eV Å0.5]	0.000
Plasma frequency (y) [eV Å0.5]	0.000
Energy [eV]	-18.454
ICSD id of parent bulk structure	ICSD 96620
COD id of parent bulk structure	COD 9012705
Mono/few-layer report(s)	10.1126/science.1102896
Magnetic	No
Spin axis	z
Magnetic anisotropy energy, xz [meV/unit cell]	0.000
Magnetic anisotropy energy, yz [meV/unit cell]	0.000
Topology	Z2=1,C_M=1
Energy above convex hull [eV/atom]	0.000
Heat of formation [eV/atom]	-0.007