Coupled Cluster Parametrizations of Model Field Theories and their Bargmann-Space Representations

Abstract

Coupled cluster techniques have by now been very successfully applied to numerous quantum systems of strongly-interacting particles and fields.2,8-12 One of the key features of the whole coupled cluster method (CCM) is its ability to incorporate rather naturally and at a very fundamental level, such unifying concepts as supercoherent states, generalized many-body mean fields and generalized order parameters, and exact mappings onto corresponding multilocal classical field theories. This is particularly true of the most recent version of the theory, the so-called extended coupled cluster method (ECCM). 4,6,7 In common with its predecessor, the normal coupled cluster method (NCCM) of Coester and Kummel,1 the essence of the formalism is its intrinsic universality in being able to be applied to any system governed by some underlying Schrodinger dynamics. Furthermore, the methods are both exact in principle, and capable of being systematically implemented at various levels of approximation in practice. In its most general form the CCM provides a complete dynamical description of a many-body system by formulating it in terms of a dynamical variational principle for the action.4,7