Achievement

Thermoelectric properties of molecular junctions reveal fundamental aspects of nanoscale charge transport at interfaces and are relevant to potential organic/inorganic hybrid thermoelectric materials. Quantum transport calculations typically evaluate the Seebeck coefficient (ratio between voltage difference and temperature difference across an interface) by finite differences of the transmission as a function of energy. However, in ab initio calculations this quantity is difficult to converge for realistic systems and can require very large k-grids. David Strubbe derived a new method to evaluate S via analytic derivatives, using quantities available from standard electronic-structure and transport calculations, and demonstrated how the typical method suffers from divergences at critical points in the lead bandstructure, and how his approach remedies these problems. This technique improves k-point convergence and allows more efficient and accurate calculations of Seebeck coefficients.