Evaluating Seebeck coefficient of NaxCoO2 from molecular orbital calculations

We propose the evaluations of Seebeck coefficient of NaxCoO2 (x = 0.38, 0.67, 0.76, 0.86, and 0.95) systems by Boltzmann theory: Mott expression and Fermi energy from the discrete variational (DV)-Xα molecular orbital calculation. This approach was based on molecular orbital calculations using the Na8Co21O72, Na14Co21O72, Na16Co21O72, Na18Co21O72, and Na20Co21O72 clusters to obtain the Fermi energy at the Co3d orbital of NaxCoO2 metallic for evaluating the temperature dependence of Seebeck coefficient values. The evaluated Seebeck coefficient of the NaxCoO2 systems increases with increasing temperature as well as with increasing x value and temperature.