Disordered quantum dots: A diffusion quantum Monte Carlo study

We report diffusion quantum Monte Carlo (DQMC) calculations of disordered quantum dots in the presence of an external magnetic field. The addition spectra, spin configuration, Hund’s rule, and many-body densities are investigated up to 13 electrons. The data from DQMC is in excellent agreement with exact diagonalization for disorder-free quantum dots, and in marked difference with those obtained from unrestricted Hartree-Fock method. The energetic competition to electron-electron interaction due to disorder is found to change the transition energy between spin states, but the closed shell Hund’s rule is maintained for the disorder strength considered here. The DQMC many-body density is found to be rather smooth.