We calculate the lowest-order quantum-interference correction to the density of states (DOS) of weakly-disordered two-dimensional (2D) tight-binding square lattices around half filling. The impurities are assumed to b...We calculate the lowest-order quantum-interference correction to the density of states (DOS) of weakly-disordered two-dimensional (2D) tight-binding square lattices around half filling. The impurities are assumed to be randomly distributed on small fractions of the sites, and have a-strong potential yielding a unitary-limit scattering. In addition to the usual diffusive modes in the retarded-advanced channel, there appear diffusive pi modes in the retarded-retarded (or advanced-advanced) channel due to the existence of particle-hole symmetry. It is found that the pi-mode diffuson gives rise to a logarithmic suppression to the DOS near the band center, which prevails over the positive correction contributed by pi-mode cooperon. As a result, the DOS is subject to a negative total correction. This result is qualitatively different from the divergent behavior of the DOS at the band center predicted previously for disordered 2D two-sublattice models with the particle-hole symmetry.展开更多
In this paper, we study Lie symmetry and conserved quantities for a mechanical-electrical system. The criterion of the Lie symmetry for this system is given. The generalized Hojman conserved quantity and generalized L...In this paper, we study Lie symmetry and conserved quantities for a mechanical-electrical system. The criterion of the Lie symmetry for this system is given. The generalized Hojman conserved quantity and generalized Lutzky conserved quantity deduced from the Lie symmetry for the system are obtained. An example is presented to illustrate the results.展开更多
文摘We calculate the lowest-order quantum-interference correction to the density of states (DOS) of weakly-disordered two-dimensional (2D) tight-binding square lattices around half filling. The impurities are assumed to be randomly distributed on small fractions of the sites, and have a-strong potential yielding a unitary-limit scattering. In addition to the usual diffusive modes in the retarded-advanced channel, there appear diffusive pi modes in the retarded-retarded (or advanced-advanced) channel due to the existence of particle-hole symmetry. It is found that the pi-mode diffuson gives rise to a logarithmic suppression to the DOS near the band center, which prevails over the positive correction contributed by pi-mode cooperon. As a result, the DOS is subject to a negative total correction. This result is qualitatively different from the divergent behavior of the DOS at the band center predicted previously for disordered 2D two-sublattice models with the particle-hole symmetry.
文摘In this paper, we study Lie symmetry and conserved quantities for a mechanical-electrical system. The criterion of the Lie symmetry for this system is given. The generalized Hojman conserved quantity and generalized Lutzky conserved quantity deduced from the Lie symmetry for the system are obtained. An example is presented to illustrate the results.
