JVASP-19270_Mg2Nb2CoO8
JARVIS-ID:JVASP-19270 Functional:optB88-vdW Primitive cell Primitive cell Conventional cell Conventional cell
Chemical formula:Mg2Nb2CoO8 Formation energy/atom (eV):-2.531 a 5.161 Å α:107.538 ° a 18.929 Å α:90.0 °
Space-group :C2/c, 15 Relaxed energy/atom (eV):-5.7922 b 5.982 Å β:90.917 ° b 5.982 Å β:90.961 °
Calculation type:Bulk SCF bandgap (eV):0.026 c 9.926 Å γ:89.998 ° c 5.161 Å γ:90.0 °
Crystal system:monoclinic Point group:2/m Density (gcm-3):4.79 Volume (3):292.19 nAtoms_prim:26 nAtoms_conv:52
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Convergence [Reference]

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.


Structural analysis [Reference]

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.


Electrostatic potential [Reference]

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.


Thermoelectric properties [Reference]

Thermoelectric properties are calculated using BoltzTrap code [Source-code]. Electron and hole mass tensors (useful for semiconductors and insulators mainly)are given at 300 K [Source-code]. Following plots show the Seebeck coefficient and ZT factor (eigenvalues of the tensor shown) at 300 K along three different crystallographic directions. Seebeck coefficient and ZT plots can be compared for three different temperatures available through the buttons given below. Generally very high Kpoints are needed for obtaining thermoelectric properties. We assume the Kpoints obtained from above convergence were sufficient [Source-code].

WARNING: Constant relaxation time approximation (10-14 s) and only electronic contribution to thermal conductivity were utilized for calculating ZT.

Electron mass tensor (me unit)

0.0 0.0 -0.0
0.0 0.0 -0.0
-0.0 -0.0 0.04

Hole mass tensor (me unit)

0.0 0.0 -0.0
0.0 0.0 -0.0
-0.0 -0.0 0.04

n-& p-type Seebeck coeff. (µV/K), power-factor (µW/(mK2)), conductivity (1/(*m)), zT (assuming lattice part of thermal conductivity as 1 W/(mK)) at 600K and 1020 cm-3 doping. For mono/multi-layer materials consider Seebeck-coeff only.)

Property xx yy zz
n-Seebeck -40.69 -14.23 72.98
n-PowerFactor 0.68 11.56 13.69
n-Conductivity 107.83 8270.44 57806.77
n-ZT 0.0 0.0 0.01
p-Seebeck -38.17 -14.85 73.06
p-PowerFactor 0.69 11.78 12.5
p-Conductivity 111.3 8086.96 57360.05
p-ZT 0.0 0.0 0.01

Magnetic moment [Reference]

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: 6.0 μB

Magnetic moment per atom: 0.230769230769 μB

Magnetization
Elementsspdtot
Mg0.00.00.00.0
Mg0.00.00.00.0
Mg0.00.00.00.0
Mg0.00.00.00.0
Nb0.0030.0040.0590.066
Nb0.0030.0040.0590.066
Nb0.0030.0040.0590.066
Nb0.0030.0040.0590.066
Co0.0080.0072.5152.53
Co0.0080.0072.5152.53
O0.0050.0310.00.036
O0.0050.0310.00.036
O0.0050.0310.00.036
O0.0050.0310.00.036
O0.010.0730.00.083
O0.010.0730.00.083
O0.010.0730.00.083
O0.010.0730.00.083
O0.00.010.00.011
O0.00.010.00.011
O0.00.0050.00.005
O0.00.0050.00.005
O0.00.0050.00.005
O0.00.0050.00.005
O0.00.010.00.011
O0.00.010.00.011

See also

Links to other databases or papers are provided below


mvc-3391

MP link
mvc-3391

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