Localisation in topologically disordered systems

摘要: The authors study a one-electron tight-binding Hamiltonian with topological disorder using the novel concept of 'quantum connectivity'. off-diagonal matrix elements are taken to be form J(ij)=-V0e-r(ij)a(B)/, and J(ij)=-V0(1+-4(ij)a(B)/) e-r(ij)a(B)/, where rij is distance between sites i j, diagonal all zero. In three dimensions dimensionless parameter R=n13/aB, n concentration sites, characterises disorder. They find that an Anderson transition takes place at Rc=0.257+or-0.010 Rc=0.220+or-0.026 for two models respectively. also calculate correlation length exponents in each case, finding v=1.95+or-0.13 v=1.63+or-0.17 they do not observe transition.