DIPOLE INTERACTION TREATMENT OF THE POLARIZABILITIES AND LOW-ENERGY PI-PI-STAR TRANSITIONS OF AMIDES OF FORMIC-ACID AND ACETIC-ACID

Group dipole interaction theory is used to calculate polarizabiltiy tensors and Kerr constants at 589.3 nm and π-π* transition wavelengths, oscillator strengths, and polarization vectors for eight amides (formamide, acetamide, N-methylformamide, N-methylacetamide, N-t-butylformamide, N-t-butylacetamide, N,N-dimethylformamide, and N,N-dimethylacetamide). The polarizability tensor of the NC′O group is optimized to fit selected mean polarizabilities, anisotropics, and Kerr constants at 589.3 nm. The wavelength, oscillator strength, and polarization vector of the π-π* transition in the isolated NC′O group are optimized to fit selected molecular absorption wavelengths and oscillator strengths. Somewhat different NC′O parameters are found for locations of the polarizability at the NC′O mass center and the NC′ bond center. The molecular properties predicted with the mass-centered parameters give a better overall fit to molecular properties at 589.3 nm, but the bond-centered parameters lead to better Kerr constants and π-π* transition wavelengths, oscillator strengths, and polarizations. © 1979 American Institute of Physics.