of S for a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-
2,3-dithiolate) with a half-filled band, where the coefficient is obtained from a ratio of the thermal
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of S for a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-
2,3-dithiolate) with a half-filled band, where the coefficient is obtained from a ratio of the thermal
conductivity to the electrical conductivity. The present paper demonstrates theoretically the novel
result of large anisotropy in the Seebeck coefficient components of three-dimensional Dirac electrons
in a molecular conductor. The conductor exhibits a nodal line with the energy variation around
the chemical potential and provides the density of states (DOS) with a minimum. Using a threedimensional
tight-binding (TB) model in the presence of both impurity and electron–phonon (e–p)
scatterings, we study the Seebeck coefficient Sy for the molecular stacking and the most conducting
direction. The impact of T on Sy exhibits a sign change, where Sy > 0 with a maximum at high
temperatures and Sy < 0 with a minimum at low temperatures. The T dependence of Sy suggests
that the contribution from the conduction (valence) band is dominant at low (high) temperatures.
Further, it is shown that the the Seebeck coefficient components for perpendicular directions Sx and
Sz are much smaller than Sy and present no sign change, in contrast to Sy. These results are analyzed
in terms of the spectral conductivity as a function of the energy ϵ close to the chemical potential μ. Full article