Accurate Compton profiles for H₂ and D₂ including the effects of electron correlation and molecular vibration and rotation

Abstract

Accurate isotropic Compton profiles J(q,R) for H2(X 1∑g+) are calculated for 22 internuclear separations from the 126 configuration wavefunctions of Liu. These profiles, supplemented by the united atom and separated atom profiles, are then rigorously averaged over vibration-rotation wavefunctions computed by direct numerical solution of the radial Schrödinger equation using nearly exact potential energy curves including adiabatic and relativistic corrections. These averages are performed for a large number of vibration-rotation states of H2 and the ground vibration-rotation state of D2. It is shown that the effects of averaging Compton profiles over vibration-rotation states are significant and cannot be neglected. The isotope effect is shown to be smaller than the vibration-rotation effect. The peak of the calculated H2 Compton profile for the ground vibration-rotation state is found to be in excellent agreement with the very recent high energy electron impact measurements of Lee. A number of expansion techniques for vibration-rotation averaging, including a new, very simple, and reasonably accurate delta approximation, are presented. Copyright © 1977 American Institute of Physics.