Overview: S₂Sn₂

Structure info
Layer group	pm2_1n
Layer group number	32
Structure origin	adhoc_material

Stability
Energy above convex hull [eV/atom]	0.062
Heat of formation [eV/atom]	-0.396
Dynamically stable	Yes

Basic properties
Magnetic	No
Ferroelectric	Yes
Band gap (PBE) [eV]	1.834
Band gap (HSE06) [eV]	2.520

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	5.856	-0.000	0.000	Yes
2	-0.000	3.787	0.000	Yes
3	0.000	-0.000	18.000	No

Lengths [Å]	5.856	3.787	18.000
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Rectangular (op)
Layer group number	32
Layer group	pm2_1n
Space group number (bulk in AA-stacking)	31
Space group (bulk in AA-stacking)	Pmn2_1
Point group	mm2
Inversion symmetry	No

Structure data
Formula	Sn2S2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	22.178
Thickness [Å]	2.219

Stability

Convex hull

S2Sn2 (2SSn-2)
Heat of formation [eV/atom]	-0.40
Energy above convex hull [eV/atom]	0.06

Monolayers from C2DB
S4Sn4 (4SSn-1)	-0.42 eV/atom
S2Sn2 (2SSn-1)	-0.41 eV/atom
SnS2 (1SnS2-1)	-0.40 eV/atom
S2Sn2, (2SSn-2)	-0.40 eV/atom
Sn7S12 (1Sn7S12-1)	-0.38 eV/atom
Sn9S12 (3Sn3S4-1)	-0.37 eV/atom
Sn8S12 (4Sn2S3-1)	-0.36 eV/atom
SSn (1SSn-1)	-0.34 eV/atom
SnS2 (1SnS2-2)	-0.32 eV/atom
SnS2 (1SnS2-3)	-0.12 eV/atom
Sn2S4 (2SnS2-1)	-0.10 eV/atom
S2Sn2 (2SSn-3)	-0.10 eV/atom
Sn2S6 (2SnS3-1)	-0.08 eV/atom
S2Sn2 (2SSn-4)	-0.02 eV/atom
Sn4 (4Sn-1)	0.26 eV/atom
Sn2 (2Sn-1)	0.44 eV/atom
S2 (2S-1)	0.45 eV/atom
S2 (2S-2)	0.62 eV/atom

Bulk crystals from OQMD123
S4Sn4	-0.46 eV/atom
S2Sn	-0.40 eV/atom
S48	0.00 eV/atom
Sn2	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Deformation potentials

DVB [eV]	xx	yy	xy
Γ	-3.14	1.91	0.00
X	-2.66	2.97	0.00
S	-2.98	0.84	0.93
Y	-3.91	0.86	0.00
kVBM	-3.36	2.11	0.00

	xx	yy	xy
Band gap [eV]	1.16	2.33	0.00

DCB [eV]	xx	yy	xy
Γ	0.99	-6.44	-0.00
X	-0.25	-4.68	0.00
S	-2.52	3.73	-0.39
Y	-2.11	3.86	0.00
kCBM	-2.21	4.44	0.00

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	18.86	3.07	-0.00
yy	2.41	26.61	0.00
xy	0.00	0.00	17.29

Stiffness tensor eigenvalues
Eigenvalue 0	17.29 N/m
Eigenvalue 1	18.00 N/m
Eigenvalue 2	27.46 N/m

Piezoelectric tensor

cij [e/Å]	xx	yy	xy
x	-1.33	-0.06	0.00
y	-0.00	-0.00	-0.04
z	-0.00	0.00	0.00

cijclamped [e/Å]	xx	yy	xy
x	0.16	-0.08	0.00
y	0.00	0.00	-0.04
z	-0.00	-0.00	0.00

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	1.834
Direct band gap (PBE)	1.923
Valence band maximum wrt. vacuum (PBE)	-5.048
Conduction band minimum wrt. vacuum (PBE)	-3.213

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	2.520
Direct band gap (HSE06)	2.624
Valence band maximum wrt. vacuum (HSE06)	-5.505
Conduction band minimum wrt. vacuum (HSE06)	-2.985

Effective masses

Property (VBM)	Value
Min eff. mass	0.91 m0
Max eff. mass	1.67 m0
DOS eff. mass	1.24 m0
Crystal coordinates	[0.000, -0.160]
Warping parameter	-0.000
Barrier height	> 20.3 meV
Distance to barrier	> 0.0165 Å-1

Property (CBM)	Value
Min eff. mass	0.40 m0
Max eff. mass	1.03 m0
DOS eff. mass	0.64 m0
Crystal coordinates	[0.000, -0.356]
Warping parameter	0.001
Barrier height	> 39.1 meV
Distance to barrier	> 0.0165 Å-1

Electronic properties

Born charges

ZSnij	ux	uy	uz
Px	3.86	0.00	0.16
Py	0.00	2.60	-0.00
Pz	-0.07	0.00	0.38

ZSij	ux	uy	uz
Px	-3.86	-0.00	-0.71
Py	0.00	-2.60	-0.00
Pz	-0.09	0.00	-0.38

ZSnij	ux	uy	uz
Px	3.86	0.00	-0.16
Py	-0.00	2.60	0.00
Pz	0.07	0.00	0.38

ZSij	ux	uy	uz
Px	-3.86	0.00	0.71
Py	0.00	-2.60	0.00
Pz	0.09	-0.00	-0.38

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Sn	0.94
1	Sn	0.94
2	S	-0.94
3	S	-0.94

Spontaneous polarization

Spontaneous polarization vector component [pC/m]
Px	-122.904
Py	-0.000
Pz	0.000

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	3.856
Interband polarizability (y) [Å]	2.423
Interband polarizability (z) [Å]	0.338

Infrared polarizability

Static polarizability [Å]
Phonons only (x)	24.87
Phonons only (y)	2.40
Phonons only (z)	0.03
Total (phonons + electrons) (x)	28.72
Total (phonons + electrons) (y)	4.83
Total (phonons + electrons) (z)	0.36

Shift current

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

Miscellaneous

Miscellaneous details
Unique ID	2SSn-2
Number of atoms	4
Number of species	2
Formula	Sn2S2
Reduced formula	SnS
Stoichiometry	AB
Unit cell area [Å2]	22.178
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/adhoc_materials/Sn2S2
Old uid	S2Sn2-a8ffaf9a2b50
Space group (bulk in AA-stacking)	Pmn2_1
Space group number (bulk in AA-stacking)	31
Point group	mm2
Inversion symmetry	No
Layer group number	32
Layer group	pm2_1n
2D Bravais type	Rectangular (op)
Thickness [Å]	2.219
Structure origin	adhoc_material
Band gap (PBE) [eV]	1.834
Direct band gap (PBE) [eV]	1.923
gap_dir_nosoc	1.948
Vacuum level [eV]	2.558
Fermi level wrt. vacuum (PBE) [eV]	-4.131
Valence band maximum wrt. vacuum (PBE) [eV]	-5.048
Conduction band minimum wrt. vacuum (PBE) [eV]	-3.213
minhessianeig	-0.000

Miscellaneous details
Dynamically stable	Yes
Band gap (HSE06) [eV]	2.520
Direct band gap (HSE06) [eV]	2.624
Fermi level wrt. vacuum (HSE) [eV]	-4.245
Valence band maximum wrt. vacuum (HSE06) [eV]	-5.505
Conduction band minimum wrt. vacuum (HSE06) [eV]	-2.985
Interband polarizability (x) [Å]	3.856
Interband polarizability (y) [Å]	2.423
Interband polarizability (z) [Å]	0.338
Static polarizability (phonons) (x) [Å]	24.868
Static polarizability (phonons + electrons) (x) [Å]	28.723
Static polarizability (phonons) (y) [Å]	2.403
Static polarizability (phonons + electrons) (y) [Å]	4.826
Static polarizability (phonons) (z) [Å]	0.026
Static polarizability (phonons + electrons) (z) [Å]	0.364
Energy [eV]	-17.852
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
Ferroelectric	Yes
Spontaneous polarization [pC/m]	122.904
Energy above convex hull [eV/atom]	0.062
Heat of formation [eV/atom]	-0.396