English

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

Quantum Physics 2025-01-03 v5

Abstract

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 ensemble states. By means of a toy model we show that the RRM eigenvalues approach to those of the projected Hamiltonian from below in most cases but a few ones. We also discuss the effect of an energy shift and the projection of the identity operator.

Keywords

Cite

@article{arxiv.2411.14490,
  title  = {On the application of the Rayleigh-Ritz method to a projected Hamiltonian},
  author = {Francisco M. Fernández},
  journal= {arXiv preprint arXiv:2411.14490},
  year   = {2025}
}