Vibrational Force Field for 1-Butyne and Propionitrile

Abstract Normal coordinate calculations were made for 1-butyne and propionitrile, using a thirty-parameter modified valence force field. Only the C=X stretching force constant was assumed to be different in the two molecules. Fifteen force constants were refined to fit forty frequencies of the two molecules, with the average error being only 2.0 cm−1, or 0.16%.