We have employed the radiative forcing function recently computed by Pinnock et al. <1995>, in conjunction with infrared cross sections and vibrational frequencies calculated with ab initio quantum-mechanical methods, to estimate the instantaneous infrared radiative forcing terms tot of a number of CFC substitutes and their atmospheric reaction products. The computed quantities tot are compared with those obtained by Pinnock et al. <1995> employing experimental infrared spectra. In particular, Gaussian-92™ software has been utilized, at the MP2/6-31G** level of theory, to provide computational estimates of these quantities. Our results agree with the former, with a mean and a standard deviation of the difference of +3% and 15%, respectively. An error analysis is provided to assess the utility of the method. The capability of quantum-mechanical computational methods to explore structural trends in radiative and physicochemical properties is exploited for the molecular systems examined here.¿ 1997 American Geophysical Union