The relative contributions of nuclear repulsion and electronic attraction to conformational rotational potentials have been analysed for several types of systems. It is shown that decomposition of a computed total energy into these two components provides a diagnostic tool for the evaluation of the reliability of such computations. It is also pointed out that Hartree–Fock theory is sufficient to reproduce experimental stereochemical observations, provided that one is aware of the accuracy needed to compute the molecular electronic wave function. This accuracy is predetermined by the nuclear or electronic dominance of the process.