activity
20202026
most citedOn the Raleigh-Ritz variational method. Non-orthogonal basis set

7 citations · 7 across the 16 of their papers we have counts for

collaborators

16 papers

quant-ph2026

On some potentials based on exponential functions

Francisco M. Fernández

By means of a simple and systematic normalization method we show that some apparently different potentials based on exponential functions are equivalent. Present normalization meth…

quant-ph2026

On solutions of the Schrödinger equation for some molecular potentials: Power-series method

Francisco M. Fernández

We show that the standard power-series method described in many textbooks of quantum-mechanics and quantum-chemistry is simpler and more powerful than the wavefunction approach pro…

quant-ph2025

Exact solutions, critical parameters and accidental degeneracy for the hydrogen atom in a spherical box

Francisco M. Fernández

We derive some properties of the hydrogen atom inside a box with an impenetrable wall that have not been discussed before. Suitable scaling of the Hamiltonian operator proves to be…

quant-ph2025

On the two-dimensional hydrogen atom in a circular box in the presence of an electric field

Paolo Amore, Francisco M. Fernández

We revisit the quantum-mechanical two-dimensional hydrogen atom with an electric field confined to a circular box of impenetrable wall. In order to obtain the energy spectrum we re…

quant-ph2024

On the application of the Rayleigh-Ritz method to a projected Hamiltonian

Francisco M. Fernández

We apply the well known Rayleigh-Ritz method (RRM) to the projection of a Hamiltonian operator chosen recently for the extension of the Rayleigh-Ritz variational principle to ensem…

quant-ph2024

On the exact solutions of a one-dimensional Schrödinger equation with a rational potential

Francisco M. Fernández

We analyse the exact solutions of a conditionally-solvable Schrödinger equation with a rational potential. From the nodes of the exact eigenfunctions we derive a connection between…

quant-ph2024

Just another conditionally-solvable non-relativistic quantum-mechanical model

Francisco M. Fernández

We show that a perturbed Coulomb problem discussed recently is conditionally solvable. We obtain the exact eigenvalues and eigenfunctions and compare the former with eigenvalues ca…

quant-ph2024

On the two-dimensional harmonic oscillator with an electric field confined to a circular box

Francisco M. Fernández, Javier Garcia, Norberto Aquino +1

We revisit the quantum-mechanical two-dimensional harmonic oscillator with an electric field confined to a circular box of impenetrable walls. In order to obtain the energy spectru…

quant-ph2024

The Hellmann-Feynman theorem and the spectrum of some Hamiltonian operators

Paolo Amore, Francisco M. Fernández

In this short note we resort to the well known Hellmann-Feynman theorem to prove that some non-relativistic Hamiltonian operators support an infinite number of bound states.

quant-ph2024

On the screened Kratzer potential and its variants

Francisco M. Fernández

We argue that several potentials proposed recently for the analysis of the vibrational-rotational spectra of diatomic molecules and their thermodynamic properties exhibit a flaw. O…

quant-ph2024★ 7 cited

On the Raleigh-Ritz variational method. Non-orthogonal basis set

Francisco M. Fernández

We overview the main equations of the Rayleigh-Ritz variational method and discuss their connection with the problem of simultaneous diagonalization of two Hermitian matrices.

quant-ph2024

On the eigenvalues of the harmonic oscillator with a Gaussian perturbation

Paolo Amore, Francisco M. Fernández, Javier Garcia

We test the analytical expressions for the first two eigenvalues of the harmonic oscillator with a Gaussian perturbation proposed recently. Our numerical eigenvalues show that thos…

quant-ph2023

On the spectrum of the screened Coulomb potential

Francisco M. Fernández

We analyse recent contradictory results and conclusions about the spectrum of the screened Coulomb potential . The well known Hellmann-Feynman theorem shows t…

quant-ph2023

On the variational treatment of a class of double-well oscillators

Francisco M. Fernández, Javier Garcia

We compare the well known Rayleigh-Ritz variational method (RRVM) with a recently proposed approach based on supersymmetric quantum mechanics and the Gram-Schmidt orthogonalization…

physics.class-ph2023

On the normal modes of coupled harmonic oscillators

Francisco M. Fernández

We discuss in detail a well known method for obtaining the frequencies of the normal modes of coupled harmonic oscillators that is based on the simultaneous diagonalization of two…

quant-ph2020

Comment on: "Harmonic oscillator in an environment with a pointlike defect". Phys. Scr. \textbf{94} ( 2019) 125301

Francisco M. Fernández

We analyze recent results for a harmonic oscillator in an environment with a pointlike defect. We show that the allowed oscillator frequencies predicted by the authors stem from a…