The Journal of Chemical Physics

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

View publication


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.