The Hartree-Fock based diagonalization—an efficient algorithm for the treatment of interacting electrons in disordered solids

The Hartree-Fock based diagonalization (HFD) is a computational method for the investigation of the low-energy properties of correlated electrons in disordered solids. The method is related to the quantum-chemical configuration interaction approach. It consists of diagonalizing the Hamiltonian in a reduced Hilbert space built of the low-energy states of the corresponding disordered Hartree-Fock (HF) Hamiltonian. The properties of the method are discussed for the example of the quantum Coulomb glass, a lattice model of electrons in a random potential interacting via long-range Coulomb interaction. Particular attention is paid to the accuracy of the results as a function of the dimension of the reduced Hilbert space. It is argued that disorder actually helps the approximation.