About Approximation of Convergence Superoperators in Quantum Perturbation Theory

Perturbation methods are generally used for solving wave operator equations associated with the determination of effective Hamiltonians. In many cases the standard Rayleigh-Schrodinger and Brillouin-Wigner series either converge slowly or diverge. Therefore it is necessary to modify or to renormalize the standard wave equations. For that purpose derivative and convergence superoperators within the Ralyeigh-Schrodinger and Brillouin-Wigner formalisms were introduced. A new efficient otential is obtained and further application to molecular dynamics is indicated.