. "Helmholtz" . . "helmholtz free energy" . . . . . . . . . "Bogoliubov inequality" . "\u0394_''f''H^o_''k''" . . . "Bogolyubov inequality" . "Helmholtz free energy" . . "free energy" . . . . . . "Helmholtz free energy" . "Gibbs-Bogoliubov inequality" . . . . "Helmholtz energy" . . . "Helmholtz free energies" .