Overview: TaSe₂

Structure info
Layer group	p-3m1
Layer group number	72
Structure origin	original03-18
COD id of parent bulk structure	COD 4031648
ICSD id of parent bulk structure	ICSD 24318
Mono/few-layer report(s)	10.1021/acs.nanolett.7b03264

Stability
Energy above convex hull [eV/atom]	0.023
Heat of formation [eV/atom]	-0.815
Dynamically stable	Yes

Basic properties
Magnetic	No
Band gap (PBE) [eV]	0.000

Repeat: 1234   Download: XYZ CIF JSON

Axis	x [Å]	y [Å]	z [Å]	Periodic
1	3.503	0.000	0.000	Yes
2	-1.751	3.034	0.000	Yes
3	-0.000	0.000	18.303	No

Lengths [Å]	3.503	3.503	18.303
Angles [°]	90.000	90.000	120.000

Crystal structure

Symmetries
2D Bravais type	Hexagonal (hp)
Layer group number	72
Layer group	p-3m1
Space group number (bulk in AA-stacking)	164
Space group (bulk in AA-stacking)	P-3m1
Point group	-3m
Inversion symmetry	Yes

Structure data
Formula	TaSe2
Stoichiometry	AB2
Number of atoms	3
Unit cell area [Å2]	10.626
Thickness [Å]	3.305

Stability

Convex hull

TaSe2 (1TaSe2-2)
Heat of formation [eV/atom]	-0.81
Energy above convex hull [eV/atom]	0.02

Monolayers from C2DB
TaSe2 (1TaSe2-1)	-0.84 eV/atom
TaSe2, (1TaSe2-2)	-0.81 eV/atom
Ta4Se6 (2Ta2Se3-1)	-0.79 eV/atom
Ta7Se12 (1Ta7Se12-1)	-0.77 eV/atom
Ta4Se12 (4TaSe3-1)	-0.68 eV/atom
Ta8Se12 (4Ta2Se3-1)	-0.66 eV/atom
Ta2Se6 (2TaSe3-1)	-0.63 eV/atom
Ta9Se12 (3Ta3Se4-1)	-0.56 eV/atom
Se2Ta4 (2SeTa2-1)	-0.49 eV/atom
Se2Ta2 (2SeTa-1)	-0.38 eV/atom
TaSe2 (1TaSe2-3)	-0.37 eV/atom
Se2Ta2 (2SeTa-2)	-0.34 eV/atom
Se2Ta2 (2SeTa-3)	-0.30 eV/atom
Se2Ta2 (2SeTa-4)	-0.13 eV/atom
Se2Ta2 (2SeTa-5)	-0.12 eV/atom
Se2 (2Se-1)	0.21 eV/atom
Se2 (2Se-2)	0.29 eV/atom

Bulk crystals from OQMD123
Se2Ta	-0.84 eV/atom
Se12Ta4	-0.68 eV/atom
Se2Ta4	-0.46 eV/atom
Se3	0.00 eV/atom
Ta	0.00 eV/atom

Phonons

Minimum eigenvalue of Hessian [eV/Ų]

-0.00

Linear deformations

Stiffness tensor

Cij (N/m)	xx	yy	xy
xx	78.40	15.70	0.01
yy	15.02	78.71	0.01
xy	0.00	0.00	62.96

Stiffness tensor eigenvalues
Eigenvalue 0	62.96 N/m
Eigenvalue 1	63.19 N/m
Eigenvalue 2	93.91 N/m

Electronic bands

Band structure and DOS

Key values [eV]
Band gap (PBE)	0.000
Direct band gap (PBE)	0.000
Fermi level wrt. vacuum (PBE)	-4.696

Fermi surface

Electronic properties

Bader charges

Atom No.	Chemical symbol	Charges [|e|]
0	Ta	1.59
1	Se	-0.79
2	Se	-0.79

Optical properties

Optical polarizability

Properties
Interband polarizability (x) [Å]	16.170
Interband polarizability (y) [Å]	16.170
Interband polarizability (z) [Å]	0.397
Plasma frequency (x) [eV Å0.5]	8.326
Plasma frequency (y) [eV Å0.5]	8.326

Raman spectrum

Mode	Frequency (1/cm)	Degeneracy
Mode 1	0.	3
Mode 2	142.4	2
Mode 3	151.2	2
Mode 4	218.2	1
Mode 5	262.4	1

Miscellaneous

Miscellaneous details
Unique ID	1TaSe2-2
Number of atoms	3
Number of species	2
Formula	TaSe2
Reduced formula	TaSe2
Stoichiometry	AB2
Unit cell area [Å2]	10.626
Original file-system folder	/home/niflheim2/cmr/C2DB-ASR/tree/AB2/TaSe2/TaSe2-e3db961ebd64
Old uid	TaSe2-e3db961ebd64
Space group (bulk in AA-stacking)	P-3m1
Space group number (bulk in AA-stacking)	164
Point group	-3m
Inversion symmetry	Yes
Layer group number	72
Layer group	p-3m1
2D Bravais type	Hexagonal (hp)
Thickness [Å]	3.305
Structure origin	original03-18
Band gap (PBE) [eV]	0.000
Direct band gap (PBE) [eV]	0.000

Miscellaneous details
gap_dir_nosoc	0.000
Vacuum level [eV]	4.278
Fermi level wrt. vacuum (PBE) [eV]	-4.696
minhessianeig	-0.000
Dynamically stable	Yes
Interband polarizability (x) [Å]	16.170
Interband polarizability (y) [Å]	16.170
Interband polarizability (z) [Å]	0.397
Plasma frequency (x) [eV Å0.5]	8.326
Plasma frequency (y) [eV Å0.5]	8.326
Energy [eV]	-19.226
ICSD id of parent bulk structure	ICSD 24318
COD id of parent bulk structure	COD 4031648
Mono/few-layer report(s)	10.1021/acs.nanolett.7b03264
Magnetic	No
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]	0.023
Heat of formation [eV/atom]	-0.815