Disorder-induced zero-energy spectral singularity for random matrices with correlations

A zero-energy midband singularity has been found in the energy spectrum of random matrices with correlations between diagonal and off-diagonal elements typical of vibrational problems. Two representative classes of matrices, characterizing the instantaneous configurations in liquids and mechanically unstable lattices (which mimic the former), have been analyzed. At least for disordered lattice models, the singularity is universal and its origin can be explained within a mean-field treatment.