| Structure info | |
|---|---|
| Layer group | pm2_1n |
| Layer group number | 32 |
| Structure origin | original03-18 |
| ICSD id of parent bulk structure | ICSD 638005 |
| Stability | |
|---|---|
| Energy above convex hull [eV/atom] | 0.054 |
| Heat of formation [eV/atom] | -0.039 |
| Dynamically stable | Yes |
| Basic properties | |
|---|---|
| Magnetic | No |
| Ferroelectric | Yes |
| Band gap (PBE) [eV] | 0.815 |
| Band gap (HSE06) [eV] | 1.103 |
| Band gap (G₀W₀) [eV] | 1.286 |
| 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 | Te2Ge2 |
| Stoichiometry | AB |
| Number of atoms | 4 |
| Unit cell area [Å2] | 18.508 |
| Thickness [Å] | 3.036 |
| Ge2Te2 (2GeTe-1) | |
|---|---|
| Heat of formation [eV/atom] | -0.04 |
| Energy above convex hull [eV/atom] | 0.05 |
| Monolayers from C2DB | |
|---|---|
| Te2Ge2, (2GeTe-1) | -0.04 eV/atom |
| TeGe (1GeTe-1) | -0.01 eV/atom |
| Te2Ge2 (2GeTe-2) | -0.00 eV/atom |
| Te2Ge (1GeTe2-1) | 0.07 eV/atom |
| Te2Ge (1GeTe2-2) | 0.08 eV/atom |
| Te4Ge2 (2GeTe2-1) | 0.14 eV/atom |
| Te2 (2Te-1) | 0.16 eV/atom |
| Te2Ge (1GeTe2-3) | 0.20 eV/atom |
| Te4Ge2 (2GeTe2-2) | 0.27 eV/atom |
| Te2 (2Te-2) | 0.29 eV/atom |
| Te2Ge2 (2GeTe-3) | 0.38 eV/atom |
| Ge2 (2Ge-1) | 0.48 eV/atom |
| Ge2 (2Ge-2) | 0.49 eV/atom |
| Minimum eigenvalue of Hessian [eV/Ų] | -0.00 |
| DVB [eV] | xx | yy | xy |
| Γ | 2.11 | 1.79 | 0.00 |
| X | -2.02 | -9.84 | 0.00 |
| S | 2.64 | 0.88 | -0.20 |
| Y | -7.99 | -0.43 | 0.00 |
| kVBM | -3.22 | -10.40 | 0.00 |
| xx | yy | xy | |
| Band gap [eV] | 2.46 | 13.68 | -0.00 |
| DCB [eV] | xx | yy | xy |
| Γ | -3.46 | -1.88 | 0.00 |
| X | 3.76 | -5.59 | 0.00 |
| S | -3.60 | -0.34 | -0.34 |
| Y | -0.37 | 3.07 | -0.00 |
| kCBM | -0.76 | 3.28 | -0.00 |
| Cij (N/m) | xx | yy | xy |
| xx | 23.97 | 13.54 | 0.01 |
| yy | 15.00 | 47.74 | 0.01 |
| xy | 0.00 | -0.00 | 49.01 |
| Stiffness tensor eigenvalues | |
| Eigenvalue 0 | 17.30 N/m |
| Eigenvalue 1 | 49.01 N/m |
| Eigenvalue 2 | 54.41 N/m |
| cij [e/Å] | xx | yy | xy |
| x | 1.12 | 0.00 | -0.00 |
| y | 0.00 | -0.00 | 1.14 |
| z | 0.00 | -0.00 | 0.00 |
| cijclamped [e/Å] | xx | yy | xy |
| x | -0.07 | -0.47 | 0.00 |
| y | 0.00 | -0.00 | -0.48 |
| z | -0.00 | -0.00 | 0.00 |
| Key values [eV] | |
|---|---|
| Band gap (PBE) | 0.815 |
| Direct band gap (PBE) | 0.872 |
| Valence band maximum wrt. vacuum (PBE) | -4.202 |
| Conduction band minimum wrt. vacuum (PBE) | -3.387 |
| Key values [eV] | |
|---|---|
| Band gap (HSE06) | 1.103 |
| Direct band gap (HSE06) | 1.140 |
| Valence band maximum wrt. vacuum (HSE06) | -4.313 |
| Conduction band minimum wrt. vacuum (HSE06) | -3.210 |
| Key values [eV] | |
|---|---|
| Band gap (G₀W₀) | 1.286 |
| Direct band gap (G₀W₀) | 1.361 |
| Valence band maximum wrt. vacuum (G₀W₀) | -4.633 |
| Conduction band minimum wrt. vacuum (G₀W₀) | -3.347 |
| Property (VBM) | Value |
|---|---|
| Min eff. mass | 0.06 m0 |
| Max eff. mass | 0.14 m0 |
| DOS eff. mass | 0.09 m0 |
| Crystal coordinates | [-0.378, -0.024] |
| Warping parameter | -0.002 |
| Barrier height | 0.0 meV |
| Distance to barrier | 0 Å-1 |
| Property (CBM) | Value |
|---|---|
| Min eff. mass | 0.05 m0 |
| Max eff. mass | 0.23 m0 |
| DOS eff. mass | 0.11 m0 |
| Crystal coordinates | [-0.000, -0.407] |
| Warping parameter | 0.001 |
| Barrier height | > 30.9 meV |
| Distance to barrier | > 0.0164 Å-1 |
| ZTeij | ux | uy | uz |
| Px | -4.20 | -0.00 | 0.05 |
| Py | -0.00 | -5.68 | -0.00 |
| Pz | -0.01 | -0.00 | -0.16 |
| ZGeij | ux | uy | uz |
| Px | 4.20 | -0.00 | 0.98 |
| Py | -0.00 | 5.68 | 0.00 |
| Pz | 0.06 | -0.00 | 0.16 |
| ZTeij | ux | uy | uz |
| Px | -4.20 | 0.00 | -0.05 |
| Py | 0.00 | -5.68 | -0.00 |
| Pz | 0.01 | -0.00 | -0.16 |
| ZGeij | ux | uy | uz |
| Px | 4.20 | 0.00 | -0.98 |
| Py | 0.00 | 5.68 | 0.00 |
| Pz | -0.06 | 0.00 | 0.16 |
| Atom No. | Chemical symbol | Charges [|e|] |
|---|---|---|
| 0 | Te | -0.40 |
| 1 | Te | -0.40 |
| 2 | Ge | 0.40 |
| 3 | Ge | 0.40 |
| Spontaneous polarization vector component [pC/m] | |
|---|---|
| Px | 314.243 |
| Py | -0.001 |
| Pz | -0.001 |
| Properties | |
|---|---|
| Interband polarizability (x) [Å] | 15.568 |
| Interband polarizability (y) [Å] | 18.472 |
| Interband polarizability (z) [Å] | 0.426 |
| Plasma frequency (x) [eV Å0.5] | 0.000 |
| Plasma frequency (y) [eV Å0.5] | 0.000 |
| Static polarizability [Å] | |
|---|---|
| Phonons only (x) | 14.68 |
| Phonons only (y) | 49.39 |
| Phonons only (z) | 0.01 |
| Total (phonons + electrons) (x) | 30.25 |
| Total (phonons + electrons) (y) | 67.86 |
| Total (phonons + electrons) (z) | 0.44 |
| Exciton binding energy (BSE) [eV] | 0.46 |
| Element | Relations |
|---|---|
| xxx | |
| xyy | |
| xzz | |
| yxy | yxy=yyx |
| Others | 0=yyy=xxz=xxy=xyz=xzx=xzy=yxx=yxz=xyx=yyz=yzx=yzy= yzz=zxx=zxy=zyx=zyy=zyz=zzy=zzz |
| zxz | zxz=zzx |
| 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 details | |
|---|---|
| Unique ID | 2GeTe-1 |
| Number of atoms | 4 |
| Number of species | 2 |
| Formula | Te2Ge2 |
| Reduced formula | TeGe |
| Stoichiometry | AB |
| Unit cell area [Å2] | 18.508 |
| Original file-system folder | /home/niflheim2/cmr/C2DB-ASR/tree/AB/GeTe/Ge2Te2-3b5fa8791e0d |
| Old uid | Ge2Te2-3b5fa8791e0d |
| 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] | 3.036 |
| Structure origin | original03-18 |
| Band gap (PBE) [eV] | 0.815 |
| Direct band gap (PBE) [eV] | 0.872 |
| gap_dir_nosoc | 0.916 |
| Vacuum level [eV] | 3.573 |
| Fermi level wrt. vacuum (PBE) [eV] | -3.795 |
| Valence band maximum wrt. vacuum (PBE) [eV] | -4.202 |
| Conduction band minimum wrt. vacuum (PBE) [eV] | -3.387 |
| minhessianeig | -0.000 |
| Dynamically stable | Yes |
| Band gap (HSE06) [eV] | 1.103 |
| Direct band gap (HSE06) [eV] | 1.140 |
| Fermi level wrt. vacuum (HSE) [eV] | -3.793 |
| Miscellaneous details | |
|---|---|
| Valence band maximum wrt. vacuum (HSE06) [eV] | -4.313 |
| Conduction band minimum wrt. vacuum (HSE06) [eV] | -3.210 |
| Band gap (G₀W₀) [eV] | 1.286 |
| Direct band gap (G₀W₀) [eV] | 1.361 |
| Fermi level wrt. vacuum (G₀W₀) [eV] | -3.994 |
| Valence band maximum wrt. vacuum (G₀W₀) [eV] | -4.633 |
| Conduction band minimum wrt. vacuum (G₀W₀) [eV] | -3.347 |
| E_B | 0.464 |
| Interband polarizability (x) [Å] | 15.568 |
| Interband polarizability (y) [Å] | 18.472 |
| Interband polarizability (z) [Å] | 0.426 |
| Static polarizability (phonons) (x) [Å] | 14.680 |
| Static polarizability (phonons + electrons) (x) [Å] | 30.248 |
| Static polarizability (phonons) (y) [Å] | 49.390 |
| Static polarizability (phonons + electrons) (y) [Å] | 67.862 |
| Static polarizability (phonons) (z) [Å] | 0.009 |
| Static polarizability (phonons + electrons) (z) [Å] | 0.436 |
| Plasma frequency (x) [eV Å0.5] | 0.000 |
| Plasma frequency (y) [eV Å0.5] | 0.000 |
| Energy [eV] | -15.598 |
| ICSD id of parent bulk structure | ICSD 638005 |
| 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] | 314.243 |
| Energy above convex hull [eV/atom] | 0.054 |
| Heat of formation [eV/atom] | -0.039 |
