2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/193419Exact solutions of Einstein equations with null Riemman-Christoffel curvature tensor everywhere, except on a hypersurface, are studied using quantum particles obeying the Klein-Gordon equation. We consider the particular cases when the curvature is represented by a Dirac delta function with support either on a sphere or on a cylinder (spherical and cylindrical shells). In particular, we analyze the necessity of extra boundary conditions on the shells.7 page,1 fig., Revtex, J. Math. Phys, in pressGeneral Relativity and Quantum Cosmologytext