It is frequently stated, on the basis of early calculations, that the multiple scattering X_α (MS X_α) method is inadequate for the calculation of potential energy surfaces. Indeed, these results have led to equilibrium geometries of linear shape for H₂O and of planar form for NH₃. These failures, which cast serious doubts on the value of the model in qualitative predictions of conformations, have been ascribed to the important error introduced by the muffin-tin approximation in the calculation of total energies. Furthermore, there is no doubt that the choice of calculation parameters (mainly the radii of atomic spheres) was rather unrealistic in these early studies. However, as substantial improvements have eventually been made to the model through the use of (i), overlapping atomic spheres (a simple way of partly relaxing the muffin-tin approximation), and (ii), a non-empirical procedure of choosing realistic calculation parameters, it seems worthwhile to undertake a new study of the H₂O and NH₃ potential energy surfaces. This study should indicate whether these developments of the model lead also to an improvement in the prediction of conformations or whether they are only advantageous in electronic structure calculations.