Abstract
A general formula is given for the cross section for the (e,2e) reaction on molecules in terms of a multicentre model for the SCF orbitals. Rotations and vibrations are taken into account. For the cases of homonuclear diatomic molecules and methane it is shown how symmetries reduce the computational labour to the point where it is possible to use the reaction as a simple test of the details of the SCF orbitals. The details of a calculation for H2 involving rotational excitations are given.