Charge oscillations in Quantum Dots: Renormalization group and Hartree method calculations

We analyze the local level occupation of a spinless, interacting two-level quantum dot coupled to two leads by means of Wilson's numerical renormalization group method. A gate voltage sweep, causing a rearrangement of the charge such that the system's energy is minimized, leads to oscillations, and sometimes even inversions, in the level occupations. These charge oscillations can be understood qualitatively by a simple Hartree analysis. By allowing a relative sign in one tunneling matrix element between dot and leads, we extend our findings to more generic models.