Boson, Symplectic and Other Replicas for Simple Hamiltonians

摘要: We present a linearization method for some simple (naturally tridiagonal) Hamiltonians. For the ground states it is equivalent to lowest approximation in coupled cluster formalism and its extension excited straightforward. Then we construct sets of Hamiltonians (boson or symplectic replicas) that produce same secular problem. In general they are not manifestly Hermitian. show how deal with this problem extract mean fields describe both normal symmetry breaking regimes at time incorporate variationally terms usually thought as correlations.