2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/163926We present a nonrelativistic wave equation for the electron in (3+1)-dimensions which includes negative-energy eigenstates. We solve this equation for three well-known instances, reobtaining the corresponding Pauli equation (but including negative-energy eigenstates) in each case.Quantum Physicstext