37 citations · 245 across the 35 of their papers we have counts for
28 papers · 1 filter
On the Hellmann-Feynman theorem for statistical averages
Francisco M. Fernández
We discuss the Hellmann-Feynman theorem for degenerate states and its application to the calculation of the derivatives of statistical averages with respect to external parameters.
On certain sum rules for the hydrogen atom
Francisco M. Fernández
We show that some sum rules for the hydrogen atom derived recently are incorrect because the authors did not take into account the continuous part of the spectrum in the sum over i…
On a perturbation treatment of a model for MHD viscous flow
Francisco M. Fernández
We discuss the solution of a nonlinear ordinary differential equation that appears in a model for MHD viscous flow caused by a shrinking sheet. We propose an accurate numerical sol…
Perturbation approaches and Taylor series
Francisco M. Fernandez
We comment on the new trend in mathematical physics that consists of obtaining Taylor series for fabricated linear and nonlinear unphysical models by means of homotopy perturbation…
On the homotopy perturbation method for Boussinesq-like equations
Francisco M. Fernández
We comment on some analytical solutions to a class of Boussinesq-like equations derived recently by means of the homotopy perturbation method (HPM). We show that one may obtain exa…
On some approximate methods for nonlinear models
Francisco M. Fernández
We show that recent applications of the homotopy perturbation method the Adomian decomposition method and the variational iteration method are completely useless for the treatment…