145 citations · 304 across the 7 of their papers we have counts for
7 papers
Particular spectral singularity in the continuum energies: a manifestation as resonances
E. Hernández, A. Jáuregui, D. Lohr +1
We study the coalescence of two bound energy eigenstates embedded in the continuous spectrum of a real Hamiltonian and the singular point produced by this coalescence. At th…
Non-Hermitian degeneracy of two unbound states
E. Hernandez, A. Jauregui, A. Mondragon
We solved numerically the implicit, trascendental equation that defines the eigenenergy surface of a degenerating isolated doublet of unbound states in the simple but illustrative…
Unfolding a degeneracy point of two unbound states: Crossings and anticrossings of energies and widths
E. Hernandez, A. Jauregui, A. Mondragon +1
We show that when an isolated doublet of unbound states of a physical system becomes degenerate for some values of the control parameters of the system, the energy hypersurfaces re…
Jordan blocks and Gamow-Jordan eigenfunctions associated to a double pole of the S-matrix
E. Hernandez, A. Jauregui, A. Mondragon
An accidental degeneracy of resonances gives rise to a double pole in the scattering matrix, a double zero in the Jost function and a Jordan chain of length two of generalized Gamo…
Accidental Degeneracy and Berry Phase of Resonant States
A. Mondragon, E. Hernandez
We study the complex geometric phase acquired by the resonant states of an open quantum system which evolves irreversibly in a slowly time dependent environment. In analogy with th…
Berry Phase of a Resonant State
A. Mondragon, E. Hernandez
We derive closed analytical expressions for the complex Berry phase of an open quantum system in a state which is a superposition of resonant states and evolves irreversibly due to…
Towards a Linear-Scaling DFT Technique: The Density Matrix Approach
E. Hernandez, C. M. Goringe, M. J. Gillan
A recently proposed linear-scaling scheme for density-functional pseudopotential calculations is described in detail. The method is based on a formulation of density functional the…