Higher Landau levels contribution to the energy of interacting electrons   in a quantum dot
  Properly regularized second-order degenerate perturbation theory is applied to compute the contribution of higher Landau levels to the low-energy spectrum of interacting electrons in a disk-shaped quantum dot. At ``filling factor'' near 1/2, this contribution proves to be larger than energy differences between states with different spin polarizations. After checking convergence of the method in small systems, we show results for a 12-electron quantum dot, a system which is hardly tractable by means of exact diagonalization techniques. 
Augusto Gonzalez (1,2), Juan David Serna (3), Roberto Capote (4), and   Guillermo Avenda\~no (1) ((1) Universidad de Antioqu...