136 citations · 736 across the 109 of their papers we have counts for
118 papers
Symmetry and degeneracy, exceptional point and coalescence: a pedagogical approach
Francisco M. Fernández
We show a parameter-dependent non-Hermitian matrix that exhibits both degeneracy and coalescence of eigenvalues at an exceptional point (Hermitian and non-Hermitian deg…
Comment on "An appropriate approach to pricing european-style options with the Adomian decomposition method"
Francisco M. Fernández
We show that the Adomian decomposition method proposed by Ke et al [ANZIAM J. \textbf{59} (2018) 349] is just the Taylor series approach in disguise. The latter approach is simpler…
Comment on "Eigenstate clustering around exceptional points"
Francisco M. Fernández
We show that the author of a recent paper [arXiv:2008.04929] put forward some false statements about the eigenstates of Hermitian and non-Hermitian systems. We conjecture that one…
Variational approach to the Schrödinger equation with a delta-function potential
Francisco M. Fernández
We obtain accurate eigenvalues of the one-dimensional Schrödinger equation with a Hamiltonian of the form , where is the Dirac delta function. We show that th…
Quasi-Hermitian one-dimensional lattice
Francisco M. Fernández
We show that a non-Hermitian operator with a tridiagonal matrix representation in a finite-dimensional vector space is similar to an Hermitian operator. The required condition is s…
Comment on: "Bound states and the potential parameter spectrum". J. Math. Phys. \textbf{67}, 062103 (2020)
Francisco M. Fernández
We analyze the application of the "tridiagonal representation approach" (TRA) to the Schrödinger equation for some simple, exactly-solvable, quantum-mechanical models. In the case…