From localization to delocalization in the quantum Coulomb glass

We numerically investigate how electron-electron interactions influence the transport properties of disordered electrons in two dimensions. Our study is based on the quantum Coulomb glass model appropriately generalized to include the spin degrees of freedom. In order to obtain the low-energy properties of this model we employ the Hartree-Fock based diagonalization, an efficient numerical method similar to the configuration interaction approach in quantum chemistry. We calculate the d.c. conductance by means of the Kubo-Greenwood formula and pay particular attention to the spin degrees of freedom. In agreement with earlier results we find that electron-electron interactions can cause delocalization. For spinful electrons this delocalization is significantly larger than for spinless electrons.