Overview: O₂K₄

Structure info
Layer group	pmmn
Layer group number	46
Structure origin	Wang23

Stability
Energy above convex hull [eV/atom]	0.095
Heat of formation [eV/atom]	-0.951
Dynamically stable	Yes

Basic properties
Magnetic	No
Band gap (PBE) [eV]	0.608
Band gap (HSE06) [eV]	1.917

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	7.759	2.210	0.000	Yes
2	4.830	5.020	0.000	Yes
3	0.000	-0.000	17.515	No

Lengths [Å]	8.068	6.966	17.515
Angles [°]	90.000	90.000	30.209

Crystal structure

Symmetries
2D Bravais type	Rectangular (op)
Layer group number	46
Layer group	pmmn
Space group number (bulk in AA-stacking)	59
Space group (bulk in AA-stacking)	Pmmn
Point group	mmm
Inversion symmetry	Yes

Structure data
Formula	K4O2
Stoichiometry	AB2
Number of atoms	6
Unit cell area [Å2]	28.279
Thickness [Å]	2.506

Stability

Convex hull

O2K4 (2OK2-2)
Heat of formation [eV/atom]	-0.95
Energy above convex hull [eV/atom]	0.10

Monolayers from C2DB
O2K4 (2OK2-1)	-0.99 eV/atom
O2K4, (2OK2-2)	-0.95 eV/atom
K4O12 (4KO3-1)	-0.69 eV/atom
K (1K-1)	0.26 eV/atom

Bulk crystals from OQMD123
K4O4	-1.08 eV/atom
K2O	-1.05 eV/atom
KO2	-0.86 eV/atom
K4O12	-0.64 eV/atom
K4	0.00 eV/atom
O8	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	16.31	7.23	-0.54
yy	7.48	16.47	0.08
xy	-0.56	0.16	20.33

Stiffness tensor eigenvalues
Eigenvalue 0	9.02 N/m
Eigenvalue 1	20.33 N/m
Eigenvalue 2	23.77 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.608
Direct band gap (PBE)	0.608
Valence band maximum wrt. vacuum (PBE)	-1.922
Conduction band minimum wrt. vacuum (PBE)	-1.314

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	1.917
Direct band gap (HSE06)	1.951
Valence band maximum wrt. vacuum (HSE06)	-3.136
Conduction band minimum wrt. vacuum (HSE06)	-1.218

Electronic properties

Born charges

ZKij	ux	uy	uz
Px	1.02	-0.03	0.12
Py	-0.03	1.02	0.12
Pz	0.08	0.08	0.23

ZKij	ux	uy	uz
Px	1.02	-0.03	0.12
Py	-0.03	1.02	0.12
Pz	0.08	0.08	0.23

ZOij	ux	uy	uz
Px	-2.05	0.07	0.00
Py	0.07	-2.04	0.00
Pz	0.00	-0.00	-0.45

ZKij	ux	uy	uz
Px	1.02	-0.03	-0.12
Py	-0.03	1.02	-0.12
Pz	-0.08	-0.08	0.23

ZKij	ux	uy	uz
Px	1.02	-0.03	-0.12
Py	-0.03	1.02	-0.12
Pz	-0.08	-0.08	0.23

ZOij	ux	uy	uz
Px	-2.05	0.07	-0.00
Py	0.07	-2.04	-0.00
Pz	-0.00	0.00	-0.45

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	K	0.73
1	K	0.73
2	K	0.73
3	K	0.73
4	O	-1.47
5	O	-1.47

Berry phase spectrum

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	1.410
Interband polarizability (y) [Å]	1.411
Interband polarizability (z) [Å]	0.400

Miscellaneous

Miscellaneous details
Unique ID	2OK2-2
Number of atoms	6
Number of species	2
Formula	K4O2
Reduced formula	K2O
Stoichiometry	AB2
Unit cell area [Å2]	28.279
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree_Wang23/AB2/OK2/O2K4-2630fb3a86b1
Old uid	O2K4-99e16c640c76
Space group (bulk in AA-stacking)	Pmmn
Space group number (bulk in AA-stacking)	59
Point group	mmm
Inversion symmetry	Yes
Layer group number	46
Layer group	pmmn
2D Bravais type	Rectangular (op)
Thickness [Å]	2.506
Structure origin	Wang23
Band gap (PBE) [eV]	0.608
Direct band gap (PBE) [eV]	0.608
gap_dir_nosoc	0.608
Vacuum level [eV]	1.362

Miscellaneous details
Fermi level wrt. vacuum (PBE) [eV]	-1.618
Valence band maximum wrt. vacuum (PBE) [eV]	-1.922
Conduction band minimum wrt. vacuum (PBE) [eV]	-1.314
minhessianeig	-0.000
Dynamically stable	Yes
Band gap (HSE06) [eV]	1.917
Direct band gap (HSE06) [eV]	1.951
Fermi level wrt. vacuum (HSE) [eV]	-2.177
Valence band maximum wrt. vacuum (HSE06) [eV]	-3.136
Conduction band minimum wrt. vacuum (HSE06) [eV]	-1.218
Interband polarizability (x) [Å]	1.410
Interband polarizability (y) [Å]	1.411
Interband polarizability (z) [Å]	0.400
Energy [eV]	-20.830
Magnetic	No
Total magnetic moment [μB]	0.000
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]	0.095
Heat of formation [eV/atom]	-0.951