Short Range Interactions in Diatomic Molecules

Ab-initio molecular orbital calculations are being carried out to study many-body effects for diatomic molecules in the close-in repulsive region. Preliminary results are reported here for H2, N2 and CO. These results indicate that at least 4-body terms must be considered to obtain a good description of the potential for H2 at separations below 1.8 A°. In N2 and CO 3-body effects appear to become significant at separations below 2.8 A°.