| JARVIS-ID:JVASP-26395 | Functional:optB88-vdW | Primitive cell | Primitive cell | Conventional cell | Conventional cell |
| Chemical formula:Ca4Bi2O | Formation energy/atom (eV):-1.677 | a 4.738 Å | α:105.448 ° | a 4.738 Å | α:90.0 ° |
| Space-group :I4/mmm, 139 | Relaxed energy/atom (eV):-2.1433 | b 4.738 Å | β:105.448 ° | b 4.738 Å | β:90.0 ° |
| Calculation type:Bulk | SCF bandgap (eV):0.837 | c 8.894 Å | γ:90.0 ° | c 16.477 Å | γ:90.0 ° |
| Crystal system:tetragonal | Point group:4/mmm | Density (gcm-3):5.34 | Volume (Å3):184.96 | nAtoms_prim:7 | nAtoms_conv:14 |
Calculations are done using VASP software [Source-code]. Convergence on KPOINTS [Source-code] and ENCUT [Source-code] is done with respect to total energy of the system within 0.001 eV tolerance. Please note convergence on KPOINTS and ENCUT is generally done for target properties, but here we assume energy-convergence with 0.001 eV should be sufficient for other properties also. The points on the curves are obtained with single-point calculation (number of ionic steps, NSW=1 ). However, for very accurate calculations, NSW>1 might be needed.
The following shows the X-ray diffraction (XRD)[Source-code] pattern and the Radial distribution function (RDF) plots [Source-code]. XRD peaks should be comparable to experiments for bulk structures. Relative intensities may differ. For mono- and multi-layer structures , we take the z-dimension during DFT calculation for XRD calculations, which may differ from the experimental set-up.
The following plot shows the plane averaged electrostatic potential (ionic+Hartree) along x, y and z-directions. The red line shows the Fermi-energy while the green line shows the maximum value of the electrostatic potential. For slab structures (with vacuum along z-direction), the difference in these two values can be used to calculate work-function of the material.
Single point DFT calculation was carried out with meta-gga MBJ potential [Source-code]. This should give reasonable bandgap, and optical properties assuming the calculation was properly converged. Incident photon energy dependence of optical is shown below. Only interband optical transitions are taken into account. Also, ionic contributions were neglected.
MBJ bandgap is : 1.1983 eV
Static real-parts of dielectric function in x,y,z: 9.21,9.2,8.43
Theoretical solar-cell efficiency (in %) was calculated using spectroscopy limited maximum efficiency (SLME) and TBmBJ for the material with 500 nm thickness and at 300 K. Note that generally there are many factors that contribute towards the efficiency, such as carrier effective mass etc.
SLME is: 25.44
Elastic tensor calculated for the conventional cell of the system with finite-difference method [Source-code]. For bulk structures, elastic constants are given in GPa unit . For layered materials, the elastic constants are rescaled with respect to vacuum padding (see the input files) and the units for elastic coefficients are in N/m . Phonons obtained [Source-code] from this calculation are also shown.
WARNING: Please note we provide finite-size cell phonons only. At least 1.2 nm x1.2 nm x1.2 nm size cell or more is generally needed for obtaining reliable phonon spectrum, but we take conventional cell of the structure only. For systems having primitive-cell phonon representation tables, I denotes infrared activity and R denotes Raman active modes (where applicabale). Selection of particular q-point mesh can give rise to unphysical negative modes in phonon density of states and phonon bandstructre. The minimum thermal conductivity was calculated using elastic tensor information following Clarke and Cahill formalism.
Voigt-bulk modulus (KV): 48.81 GPa, Voigt-shear modulus (GV): 32.53 GPa
Reuss-bulk modulus (KR): 48.65 GPa, Reuss-shear modulus (GR): 31.16 GPa
Poisson's ratio: 0.23, Elastic anisotropy parameter: 0.22
Clarke's lower limit of thermal conductivity (W/(m.K)): 0.52
Cahill's lower limit of thermal conductivity (W/(m.K)): 0.57
| 99.4 | 25.1 | 25.9 | 0.0 | -0.0 | -0.0 |
| 25.1 | 99.4 | 25.9 | 0.0 | -0.0 | -0.0 |
| 25.9 | 25.9 | 86.7 | 0.0 | 0.0 | -0.0 |
| 0.0 | 0.0 | 0.0 | 42.5 | 0.0 | 0.0 |
| -0.0 | -0.0 | 0.0 | 0.0 | 25.3 | 0.0 |
| -0.0 | -0.0 | -0.0 | 0.0 | 0.0 | 25.3 |
| Phonon mode (cm-1) |
|---|
| -0.11 |
| 0.02 |
| 0.02 |
| 29.82 |
| 56.09 |
| 59.99 |
| 62.56 |
| 73.3 |
| 79.32 |
| 88.68 |
| 118.73 |
| 122.3 |
| 125.99 |
| 137.85 |
| 140.57 |
| 140.96 |
| 142.87 |
| 145.36 |
| 146.16 |
| 155.6 |
| 155.65 |
| 158.33 |
| 180.79 |
| 237.88 |
| 238.25 |
| 290.23 |
| 312.27 |
| 321.2 |
| 321.87 |
point_group_type: 4/mmm
| Phonon mode (cm-1) | Visualize Phonons hereRepresentation |
|---|---|
| -0.11 | A2u I |
| 0.02 | Eu I |
| 59.99 | Eg R |
| 79.32 | A2u I |
| 88.68 | A1g R |
| 118.73 | Eu I |
| 140.96 | A2u I |
| 142.87 | Eu I |
| 145.36 | Eg R |
| 155.6 | B2u |
| 158.33 | A1g R |
| 237.88 | Eu I |
| 290.23 | A2u I |
| 321.2 | Eu I |
The orbital magnetic moment was obtained after SCF run. This is not a DFT+U calculation, hence the data could be used to predict zero or non-zero magnetic moment nature of the material only.
Total magnetic moment: -0.0 μB
Magnetic moment per atom: -0.0 μB
| Elements | s | p | d | tot |
| Ca | -0.0 | -0.0 | -0.0 | -0.0 |
| Ca | -0.0 | -0.0 | -0.0 | -0.0 |
| Bi | 0.0 | -0.0 | 0.0 | -0.0 |
| Ca | -0.0 | -0.0 | -0.0 | -0.0 |
| Bi | 0.0 | -0.0 | 0.0 | -0.0 |
| Ca | -0.0 | -0.0 | -0.0 | -0.0 |
| O | 0.0 | 0.0 | 0.0 | 0.0 |
Links to other databases or papers are provided below
ICSD-ID: 416137
AFLOW link