{
  "id": "2408.03970",
  "version": "v1",
  "published": "2024-08-06T23:26:28.000Z",
  "updated": "2024-08-06T23:26:28.000Z",
  "title": "Thermal quasi-particle theory",
  "authors": [
    "So Hirata"
  ],
  "categories": [
    "cond-mat.stat-mech",
    "physics.chem-ph",
    "physics.comp-ph"
  ],
  "abstract": "The widely used thermal Hartree-Fock (HF) theory is generalized to include the effect of electron correlation while maintaining its quasi-independent-particle framework. An electron-correlated internal energy (or grand potential) is defined by the second-order finite-temperature many-body perturbation theory (MBPT), which then dictates the corresponding thermal orbital (quasi-particle) energies in such a way that all thermodynamic relations are obeyed. The associated density matrix is of the one-electron type, whose diagonal elements take the form of the Fermi-Dirac distribution functions, when the grand potential is minimized. The formulas for the entropy and chemical potential are unchanged from those of Fermi-Dirac or thermal HF theory. The theory thus postulates a finite-temperature extension of the second-order Dyson self-energy of one-particle many-body Green's function theory and can be viewed as a second-order, diagonal, frequency-independent, thermal inverse Dyson equation. At low temperature, the theory approaches finite-temperature MBPT of the same order, but it outperforms the latter at intermediate temperature by including additional electron-correlation effects through orbital energies. A physical meaning of these thermal orbital energies (including that of thermal HF orbital energies, which has been elusive) is proposed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-08-06T23:26:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "thermal quasi-particle theory",
      "second-order finite-temperature many-body perturbation theory",
      "one-particle many-body greens function theory",
      "grand potential",
      "thermal hf orbital energies"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}