Mechanism for large thermoelectric power in molecular quantum dots described by the negative-U Anderson model

We investigate, with the aid of numerical renormalization group techniques, the thermoelectric properties of a molecular quantum dot described by the negative-U Anderson model. We show that the charge Kondo effect provides a mechanism for enhanced thermoelectric power via a correlation-induced asymmetry in the spectral function close to the Fermi level. We show that this effect results in a dramatic enhancement of the Kondo-induced peak in the thermopower of negative-U systems with Seebeck coefficients exceeding 50 mu V/K over a wide range of gate voltages.