  We study the spin-1/2 single-channel Anderson impurity model with correlated
(occupancy dependent) hybridization for molecular transistors using the
numerical renormalization-group method. Correlated hybridization can induce
nonuniversal deviations in the normalized zero-bias conductance and, for some
parameters, modestly enhance the spin polarization of currents in applied
magnetic field. Correlated hybridization can also explain a gate-voltage
dependence to the Kondo scale similar to what has been observed in recent
experiments.
