Because the L-VSCF/L-VCI approach is parameter-free, it will be particularly useful for the interpretation of 2D IR spectra in cases in which no reliable empirical exciton models are available, i.e., if vibrations other than the amide I region in polypeptides or the stretching vibrations in water are examined. Examples include 2D IR spectroscopy of nucleic acid bases or DNA and the 2D IR spectroscopy of polypeptides beyond the amide I region, which we plan to address in the future.