Overview: S₂Sn₂

Structure info
Layer group	p4/mmm
Layer group number	61
Structure origin	original03-18

Stability
Energy above convex hull [eV/atom]	0.433
Heat of formation [eV/atom]	-0.025
Dynamically stable	No

Basic properties
Magnetic	No
Band gap (PBE) [eV]	0.067
Band gap (HSE06) [eV]	0.075

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	5.576	-0.000	0.000	Yes
2	0.000	5.576	0.000	Yes
3	-0.000	0.000	15.000	No

Lengths [Å]	5.576	5.576	15.000
Angles [°]	90.000	90.000	90.000

Crystal structure

Symmetries
2D Bravais type	Square (tp)
Layer group number	61
Layer group	p4/mmm
Space group number (bulk in AA-stacking)	123
Space group (bulk in AA-stacking)	P4/mmm
Point group	4/mmm
Inversion symmetry	Yes

Structure data
Formula	S2Sn2
Stoichiometry	AB
Number of atoms	4
Unit cell area [Å2]	31.089
Thickness [Å]	0.000

Stability

Convex hull

S2Sn2 (2SSn-4)
Heat of formation [eV/atom]	-0.02
Energy above convex hull [eV/atom]	0.43

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]

-7.26

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	51.64	7.35	-0.00
yy	7.35	51.64	-0.00
xy	0.00	0.00	1.28

Stiffness tensor eigenvalues
Eigenvalue 0	1.28 N/m
Eigenvalue 1	44.29 N/m
Eigenvalue 2	58.99 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.067
Direct band gap (PBE)	0.121
Valence band maximum wrt. vacuum (PBE)	-3.881
Conduction band minimum wrt. vacuum (PBE)	-3.814

Electronic band structure (HSE06@PBE)

Key values [eV]
Band gap (HSE06)	0.075
Direct band gap (HSE06)	0.145
Valence band maximum wrt. vacuum (HSE06)	-3.746
Conduction band minimum wrt. vacuum (HSE06)	-3.671

Effective masses

Property (VBM)	Value
Min eff. mass	0.08 m0
Max eff. mass	0.78 m0
DOS eff. mass	0.26 m0
Crystal coordinates	[0.412, 0.463]
Warping parameter	-0.000
Barrier height	0.0 meV
Distance to barrier	0 Å-1

Property (CBM)	Value
Min eff. mass	0.11 m0
Max eff. mass	0.51 m0
DOS eff. mass	0.24 m0
Crystal coordinates	[0.418, 0.418]
Warping parameter	0.043
Barrier height	> 68.9 meV
Distance to barrier	> 0.015 Å-1

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Sn	1.03
1	Sn	1.03
2	S	-1.04
3	S	-1.04

Berry Phase Spectrum

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	5.678
Interband polarizability (y) [Å]	5.678
Interband polarizability (z) [Å]	0.219
Plasma frequency (x) [eV Å0.5]	1.844
Plasma frequency (y) [eV Å0.5]	1.844

Optical absorption (BSE and RPA)

Exciton binding energy (BSE) [eV]

0.34

Miscellaneous

Miscellaneous details
Unique ID	2SSn-4
Number of atoms	4
Number of species	2
Formula	S2Sn2
Reduced formula	SSn
Stoichiometry	AB
Unit cell area [Å2]	31.089
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB/SSn/S2Sn2-b8e2ee0faa87
Old uid	S2Sn2-b8e2ee0faa87
Space group (bulk in AA-stacking)	P4/mmm
Space group number (bulk in AA-stacking)	123
Point group	4/mmm
Inversion symmetry	Yes
Layer group number	61
Layer group	p4/mmm
2D Bravais type	Square (tp)
Thickness [Å]	0.000
Structure origin	original03-18
Band gap (PBE) [eV]	0.067
Direct band gap (PBE) [eV]	0.121
gap_dir_nosoc	0.000
Vacuum level [eV]	2.135
Fermi level wrt. vacuum (PBE) [eV]	-3.847

Miscellaneous details
Valence band maximum wrt. vacuum (PBE) [eV]	-3.881
Conduction band minimum wrt. vacuum (PBE) [eV]	-3.814
minhessianeig	-7.261
Dynamically stable	No
Band gap (HSE06) [eV]	0.075
Direct band gap (HSE06) [eV]	0.145
Fermi level wrt. vacuum (HSE) [eV]	-3.728
Valence band maximum wrt. vacuum (HSE06) [eV]	-3.746
Conduction band minimum wrt. vacuum (HSE06) [eV]	-3.671
E_B	0.343
Interband polarizability (x) [Å]	5.678
Interband polarizability (y) [Å]	5.678
Interband polarizability (z) [Å]	0.219
Plasma frequency (x) [eV Å0.5]	1.844
Plasma frequency (y) [eV Å0.5]	1.844
Energy [eV]	-16.367
Magnetic	No
Spin axis	z
Magnetic anisotropy energy, xz [meV/unit cell]	0.000
Magnetic anisotropy energy, yz [meV/unit cell]	0.000
topology	C_M=2
Energy above convex hull [eV/atom]	0.433
Heat of formation [eV/atom]	-0.025