Virginia TechBowen, Samuel P.Williams, Clayton D.Mancini, Jay D.2014-04-252014-04-251984-08Bowen, S. P.;Williams, C. D.; Mancini, J. D., "Convergent methods for calculating thermodynamic Green functions," Phys. Rev. A 30, 932 (1984); DOI: http://dx.doi.org/10.1103/PhysRevA.30.9321050-2947http://hdl.handle.net/10919/47698A convergent method of approximating thermodynamic Green functions is outlined briefly. The method constructs a sequence of approximants which converges independently of the strength of the Hamiltonian's coupling constants. Two new concepts associated with the approximants are introduced: the resolving power of the approximation, and conditional creation (annihilation) operators. These ideas are illustrated on an exactly soluble model and a numerical example. A convergent expression for the scattering rate in a field theory is also derived.en-USIn CopyrightArticle - Refereedhttp://journals.aps.org/pra/abstract/10.1103/PhysRevA.30.932https://doi.org/10.1103/PhysRevA.30.932