Ab initio methods based on the second-order and higher connected moments, or cumulants,
of a reference function have seen limited use in the determination of correlation energies of …

A systematic nonperturbative scheme is implemented to calculate the ground state energy
for a wide class of strongly correlated fermion models. The scheme includes:(a) a method of …

Zero point energy of the Pullen–Edmonds Hamiltonian Page 1 J Math Chem (2008) 44:20–27
DOI 10.1007/s10910-007-9289-8 ORIGINAL PAPER Zero point energy of the Pullen–Edmonds …

Associated with each matrix element of the Generalized Moments Expansion, GMX (n, m)
there is a unique expansion for the ground state energy in terms of the “connected moments” …

A polemic arose recently about the applicability of the t-expansion method to the calculation
of the ground state energy E0 of the Rabi model. For specific choices of the trial function and …

We compare the connected-moments expansion (CMX) with the Rayleigh–Ritz variational
method in the Krylov space (RRK). As a benchmark model we choose the same two …

Much progress in the theoretical sciences is founded on the application of insight from
modern developments and techniques to approaches previously-considered unattractive …

By means of simple quantum-mechanical models we show that under certain conditions the
main assumptions of the connected moments expansion (CMX) are no longer valid. In …

We show that Prony's method provides the full solution to the nonlinear equations of the
connected-moments expansion (CMX). Knowledge of all the parameters in the CMX ansatz …

We analyze the convergence properties of the connected moments expansion (CMX) for the
Rabi Hamiltonian. To this end we calculate the moments and connected moments of the …