Gouterman was quickly promoted to assistant professor, and spent his time using quantum chemical calculations to understand the photophysical properties of porphyrins.
Gouterman's molecular models, which included symmetry arguments and configuration interactions, were able to predict the intensity differences between the absorption bands of porphyrins.
For example, the UV-Visible absorption spectra of hyper porphyrins contain red-shifted peaks and extra bands due to ligand-to-metal charge transfer (LMCT) transitions.
Amongst the complicated structures analysed by Gouterman were cytochrome P450–carbon monoxide complexes, whose electronic spectra included a split Soret band due to LMCT transitions.
[4] In the early 1980s, Gouterman acted as a sperm donor and helped a lesbian couple have a son.Through mutual acquaintances, he discovered the identity of his son and thereafter enjoyed a close relationship with him.