2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89042A few modified textbook Rayleigh-Schrödinger perturbative representations of bound states are reviewed. They were all inspired by an adaptive re-split of the Hamiltonian, using nonstandard bases and the flexibility of normalization of the wave functions.IX Int. Colloquium on Numerical Analysis and Computer Science with Applications, Plovdiv, Bulgaria, August 12 - 17, 2000 (60 min. inv. talk)Quantum Physicstext