Overview: Ag₂Br₂Se₄

Structure info
Layer group	p2_111
Layer group number	9
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.000
Heat of formation [eV/atom]	-0.184
Dynamically stable	Yes

Basic properties
Magnetic	No
Ferroelectric	Yes
Band gap (PBE) [eV]	1.237
Band gap (HSE06) [eV]	2.262

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	5.278	0.000	0.000	Yes
2	0.000	8.245	0.000	Yes
3	0.000	0.000	18.170	No

Lengths [Å]	5.278	8.245	18.170
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Rectangular (op)
Layer group number	9
Layer group	p2_111
Space group number (bulk in AA-stacking)	4
Space group (bulk in AA-stacking)	P2_1
Point group	2
Inversion symmetry	No

Structure data
Formula	Ag2Br2Se4
Stoichiometry	ABC2
Number of atoms	8
Unit cell area [Å2]	43.519
Thickness [Å]	3.622

Stability

Convex hull

Ag2Br2Se4 (2AgBrSe2-1)
Heat of formation [eV/atom]	-0.18
Energy above convex hull [eV/atom]	0.00

Monolayers from C2DB
Ag4Br4 (4AgBr-1)	-0.35 eV/atom
Ag4Br4 (4AgBr-2)	-0.34 eV/atom
Ag6Br6 (6AgBr-1)	-0.34 eV/atom
Ag2Br2 (2AgBr-1)	-0.34 eV/atom
Ag2Br2 (2AgBr-2)	-0.34 eV/atom
Ag6Br6 (6AgBr-2)	-0.34 eV/atom
Ag6Br6 (6AgBr-3)	-0.33 eV/atom
Ag2Br2 (2AgBr-3)	-0.33 eV/atom
Ag5Br5 (5AgBr-1)	-0.33 eV/atom
Ag6Br6 (6AgBr-4)	-0.32 eV/atom
Ag8Br8 (8AgBr-1)	-0.32 eV/atom
Ag12Br12 (12AgBr-1)	-0.32 eV/atom
Ag3Br3 (3AgBr-1)	-0.32 eV/atom
Ag2Br2 (2AgBr-4)	-0.31 eV/atom
Ag3Br3 (3AgBr-2)	-0.31 eV/atom
Ag3Br3 (3AgBr-3)	-0.31 eV/atom
Ag2Br2 (2AgBr-5)	-0.30 eV/atom
Ag3Br3 (3AgBr-4)	-0.30 eV/atom
Ag8Br8 (8AgBr-2)	-0.30 eV/atom
Ag8Br8 (8AgBr-3)	-0.30 eV/atom
Ag6Br6 (6AgBr-5)	-0.30 eV/atom
AgBr (1AgBr-1)	-0.30 eV/atom
Ag2Br2 (2AgBr-6)	-0.29 eV/atom
Ag2Br4 (2AgBr2-1)	-0.24 eV/atom
Ag4Br8 (4AgBr2-1)	-0.24 eV/atom
Ag6Br12 (6AgBr2-1)	-0.23 eV/atom
Ag2Br4 (2AgBr2-2)	-0.20 eV/atom
AgBr2 (1AgBr2-1)	-0.19 eV/atom
Ag2Br6 (2AgBr3-1)	-0.19 eV/atom
Ag2Br6 (2AgBr3-2)	-0.19 eV/atom
Ag4Br8 (4AgBr2-2)	-0.19 eV/atom
Ag2Br2Se4, (2AgBrSe2-1)	-0.18 eV/atom
Ag2Br2Se4 (2AgBrSe2-2)	-0.18 eV/atom
Ag2Br6 (2AgBr3-3)	-0.18 eV/atom
Ag4Br4Se4 (4AgBrSe-1)	-0.17 eV/atom
Ag4Br12 (4AgBr3-1)	-0.16 eV/atom
AgBr3 (1AgBr3-1)	-0.16 eV/atom
Ag2Br6 (2AgBr3-4)	-0.15 eV/atom
AgBr2 (1AgBr2-2)	-0.13 eV/atom
AgBr2 (1AgBr2-3)	-0.09 eV/atom
Se2Ag4 (2SeAg2-1)	-0.09 eV/atom
Se8Ag16 (8SeAg2-1)	-0.07 eV/atom
Se2Br5 (1Se2Br5-1)	-0.06 eV/atom
Ag2Br6 (2AgBr3-5)	-0.06 eV/atom
Ag2Br2Se2 (2AgBrSe-1)	-0.03 eV/atom
Ag4Se4 (4AgSe-1)	-0.02 eV/atom
Ag2Br6 (2AgBr3-6)	0.01 eV/atom
Ag2Se2 (2AgSe-1)	0.02 eV/atom
AgSeBr2 (1AgSeBr2-1)	0.03 eV/atom
Ag8Se12 (4Ag2Se3-1)	0.03 eV/atom
Ag2Se4 (2AgSe2-1)	0.05 eV/atom
Ag2Se2 (2AgSe-2)	0.05 eV/atom
Ag2Se2 (2AgSe-3)	0.06 eV/atom
AgSe2 (1AgSe2-1)	0.11 eV/atom
SeAg2 (1SeAg2-1)	0.15 eV/atom
Ag2Se2 (2AgSe-4)	0.15 eV/atom
Ag2Se2 (2AgSe-5)	0.18 eV/atom
Ag2Se4 (2AgSe2-2)	0.19 eV/atom
Se2 (2Se-1)	0.21 eV/atom
AgSe2 (1AgSe2-2)	0.22 eV/atom
Ag2Se2 (2AgSe-6)	0.27 eV/atom
Se2 (2Se-2)	0.29 eV/atom
Ag2 (2Ag-1)	0.31 eV/atom
AgSe2 (1AgSe2-3)	0.32 eV/atom

Bulk crystals from OQMD123
AgBr	-0.32 eV/atom
Ag4Br6	-0.28 eV/atom
Br8Se8	-0.10 eV/atom
Ag8Se4	-0.07 eV/atom
Ag4	0.00 eV/atom
Br4	0.00 eV/atom
Se3	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Deformation potentials

DVB [eV]	xx	yy	xy
Γ	0.53	2.56	-0.02
X	-2.54	-1.32	-0.03
S	-0.40	-0.20	-0.02
Y	-0.70	-1.59	-0.03
kVBM	-0.70	-1.59	-0.03

	xx	yy	xy
Band gap [eV]	-2.71	0.24	-0.05

DCB [eV]	xx	yy	xy
Γ	-0.32	0.42	-0.09
X	-2.23	-0.66	-0.07
S	-2.51	-1.08	-0.06
Y	-3.41	-1.35	-0.08
kCBM	-3.41	-1.35	-0.08

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	10.11	1.41	-0.20
yy	2.07	7.42	-0.36
xy	-0.77	-0.43	5.46

Stiffness tensor eigenvalues
Eigenvalue 0	5.39 N/m
Eigenvalue 1	6.61 N/m
Eigenvalue 2	10.99 N/m

Piezoelectric tensor

cij [e/Å]	xx	yy	xy
x	0.02	-0.04	0.00
y	-0.00	-0.01	-0.04
z	0.00	0.00	0.02

cijclamped [e/Å]	xx	yy	xy
x	-0.02	0.02	-0.00
y	-0.00	0.00	0.02
z	0.00	-0.00	-0.00

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	1.237
Direct band gap (PBE)	1.243
Valence band maximum wrt. vacuum (PBE)	-5.982
Conduction band minimum wrt. vacuum (PBE)	-4.745

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	2.262
Direct band gap (HSE06)	2.267
Valence band maximum wrt. vacuum (HSE06)	-6.831
Conduction band minimum wrt. vacuum (HSE06)	-4.569

Effective masses

Property (VBM)	Value
Min eff. mass	0.86 m0
Max eff. mass	1.16 m0
DOS eff. mass	1.02 m0
Crystal coordinates	[0.012, 0.500]
Warping parameter	-0.005
Barrier height	> 8.4 meV
Distance to barrier	> 0.0118 Å-1

Property (CBM)	Value
Min eff. mass	0.66 m0
Max eff. mass	1.94 m0
DOS eff. mass	1.13 m0
Crystal coordinates	[0.001, 0.432]
Warping parameter	0.000
Barrier height	> 5.6 meV
Distance to barrier	> 0.0125 Å-1

Electronic properties

Born charges

ZBrij	ux	uy	uz
Px	-1.34	0.14	0.12
Py	0.09	-1.90	0.02
Pz	-0.00	-0.02	-0.39

ZSeij	ux	uy	uz
Px	-0.06	-0.07	-0.15
Py	0.12	-0.10	0.49
Pz	0.03	0.05	0.03

ZSeij	ux	uy	uz
Px	0.51	-0.78	-0.21
Py	-0.77	0.88	-0.23
Pz	-0.00	0.01	0.05

ZAgij	ux	uy	uz
Px	0.88	0.08	-0.67
Py	0.12	1.13	-0.26
Pz	-0.13	-0.03	0.30

ZBrij	ux	uy	uz
Px	-1.33	-0.13	-0.12
Py	-0.09	-1.90	0.02
Pz	0.00	-0.02	-0.39

ZSeij	ux	uy	uz
Px	-0.06	0.07	0.15
Py	-0.12	-0.12	0.48
Pz	-0.03	0.05	0.03

ZSeij	ux	uy	uz
Px	0.52	0.76	0.20
Py	0.76	0.87	-0.24
Pz	0.00	0.01	0.05

ZAgij	ux	uy	uz
Px	0.89	-0.07	0.68
Py	-0.11	1.13	-0.27
Pz	0.13	-0.03	0.30

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Br	-0.48
1	Br	-0.48
2	Se	0.04
3	Se	0.03
4	Se	0.09
5	Se	0.09
6	Ag	0.36
7	Ag	0.36

Spontaneous polarization

Spontaneous polarization vector component [pC/m]
Px	-126.278
Py	-0.060
Pz	-0.003

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	2.593
Interband polarizability (y) [Å]	2.399
Interband polarizability (z) [Å]	0.329

Infrared polarizability

Static polarizability [Å]
Phonons only (x)	2.66
Phonons only (y)	3.76
Phonons only (z)	0.05
Total (phonons + electrons) (x)	5.26
Total (phonons + electrons) (y)	6.16
Total (phonons + electrons) (z)	0.38

Shift current

Element	Relations
xxx
xyy
xyz	xyz=xzy
xzz
yxy	yxy=yyx
yxz	yxz=yzx
Others	0=yyy=xxz=xyx=xzx=yxx=xxy=yyz=yzy=yzz=zxx=zyy=zyz= zzy=zzz
zxy	zxy=zyx
zxz	zxz=zzx

Miscellaneous

Miscellaneous details
Unique ID	2AgBrSe2-1
Number of atoms	8
Number of species	3
Formula	Ag2Br2Se4
Reduced formula	AgBrSe2
Stoichiometry	ABC2
Unit cell area [Å2]	43.519
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/ABC2/AgBrSe2/Ag2Br2Se4-c7e3d505588c
Old uid	Ag2Br2Se4-c7e3d505588c
Space group (bulk in AA-stacking)	P2_1
Space group number (bulk in AA-stacking)	4
Point group	2
Inversion symmetry	No
Layer group number	9
Layer group	p2_111
2D Bravais type	Rectangular (op)
Thickness [Å]	3.622
Structure origin	original03-18
Band gap (PBE) [eV]	1.237
Direct band gap (PBE) [eV]	1.243
gap_dir_nosoc	1.297
Vacuum level [eV]	2.575
Fermi level wrt. vacuum (PBE) [eV]	-5.364
Valence band maximum wrt. vacuum (PBE) [eV]	-5.982
Conduction band minimum wrt. vacuum (PBE) [eV]	-4.745

Miscellaneous details
minhessianeig	-0.000
Dynamically stable	Yes
Band gap (HSE06) [eV]	2.262
Direct band gap (HSE06) [eV]	2.267
Fermi level wrt. vacuum (HSE) [eV]	-5.735
Valence band maximum wrt. vacuum (HSE06) [eV]	-6.831
Conduction band minimum wrt. vacuum (HSE06) [eV]	-4.569
Interband polarizability (x) [Å]	2.593
Interband polarizability (y) [Å]	2.399
Interband polarizability (z) [Å]	0.329
Static polarizability (phonons) (x) [Å]	2.664
Static polarizability (phonons + electrons) (x) [Å]	5.257
Static polarizability (phonons) (y) [Å]	3.763
Static polarizability (phonons + electrons) (y) [Å]	6.161
Static polarizability (phonons) (z) [Å]	0.054
Static polarizability (phonons + electrons) (z) [Å]	0.384
Energy [eV]	-24.254
Magnetic	No
Spin axis	z
Magnetic anisotropy energy, xz [meV/unit cell]	0.000
Magnetic anisotropy energy, yz [meV/unit cell]	0.000
Ferroelectric	Yes
Spontaneous polarization [pC/m]	126.278
Energy above convex hull [eV/atom]	0.000
Heat of formation [eV/atom]	-0.184