Excerpt from A Perturbation Calculation of the Elastic Scattering of Electrons by Hydrogen Atoms If the mass of the proton is taken to be infinite, one can, as an alterna -tive, take as the perturbation simply the interaction between the two electrons. (this we call the symmetric In this case the unperturbed hamiltonian is separable and the initial and final state wave functions corres ponding to it can be exhibited in closed form. This latter procedure is likely to lead to more accurate results than the former, since we include more of the interaction in our unperturbed problem. This advantage will be most pronounced in the calculation of exchange scattering. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.