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.

In this paper we develop the Hellmann-Feynman theorem in statistical mechanics without resorting to the eigenvalues and eigenvectors of the Hamiltonian operator. Present approach does not require the quantum-mechanical ...

We explore intriguing links connecting Hellmann–Feynman’s theorem to a thermodynamics information-optimizing principle based on Fisher’s information measure.

By recourse to (i) the Hellmann–Feynman theorem and (ii) the virial one, the information-optimizing principle based on Fisher’s information measure uncovers a Legendre-transform structure associated with Schrödinger’s ...

We analyze a recent discussion of one-dimensional quantum-mechanical models with a perturbation produced by a delta-function potential. We show that the authors failed to derive a correct transcendental equation for the ...