PEPTIDES FROM NON-AMINO ACID SOURCES .2. A QUANTUM-CHEMICAL STUDY OF ISOMERS OF FORMAMIDE

Ab initio molecular-orbital calculations have been carried out on nine isomers corresponding to the empirical formula of CH3NO. The near-Hartree-Fock wavefunctions were used to calculate the groundstate energies as well as dipole moments. The total energy values and transition moments of the first 12 singlet and triplet excited states have been calculated by the virtual orbital technique. These latter results were relevant to some questions in photochemistry and also gave the basis of the theoretical electronic spectra. The computed total energies for the electronic ground states of the nine isomers studied showed that fonnamide, the model compound for the peptide bond, was much more stable than the other eight isomers.