Comparison of the electronic transport of ThN against ThC

We compared the electronic heat capacity coefficient, thermal conductivity and resistivity of ThN and ThC. We found that the electronic heat capacity coefficient of both compounds was very low as evaluated using Quantum Espresso and GGA of the Perdew, Burke, and Ernzerhof (PBE) functional. The calculated electronic heat coefficient was further reduced (∼three times for ThN and four times for ThC) when the non-local hybrid functional (B3LYP) was used. QE combined with EPW code were used to calculate integrated electron-phonon coupling strength, the Eliashberg transport coupling function and electron-phonon scattering rates. The electronic resistivity was calculated using Ziman's formula for metals as implemented in EPW code and compared to the values derived from experimental data correlations. Furthermore, the effective number (neff) of electronic carriers was calculated. The electronic thermal conductivity was evaluated from the calculated electronic resistivity via Wiedemann-Franz law using the derived number of mobility electrons: nav (averaged over the temperature range 300 K–1000 K). We found that the only way to reproduce exactly the experimental electrical resistivity and electronic thermal conductivity in both ThN and ThC was to incorporate the number of electrons contributing to thermal mobility (neff), which increase with temperature. We estimated that in ThN the number of electronic carriers is two times larger and electron-phonon coupling strength lower by a factor ∼ two, which led to about five times higher electronic thermal conductivity than calculated for ThC.