Molecules-in-Molecules Fragment-Based Method for the Accurate Evaluation of Vibrational and Chiroptical Spectra for Large Molecules

Abstract

Direct evaluation of vibrational and chiroptical properties of large molecules using an accurate level of theory with large basis sets can be computationally expensive or prohibitive. The bottlenecks in such vibrational spectroscopic evaluations of large molecules can be overcome with molecules-in-molecules (MIM) fragment-based methods. This chapter provides a review of the performance of MIM methods for the calculation of vibrational and chiroptical spectroscopic properties of large molecules. It then describes the theoretical background for evaluating MIM energies and their higher derivatives to evaluate the spectroscopic properties of interest. Next, the chapter presents an assessment of the performance of MIM for a range of benchmark systems as well as a comparison of MIM vibrational and chiroptical spectra with experiment for large molecules like α-D-cyclodextrin and cryptophane-A. Finally, it describes the two-step-MIM procedure for evaluating the extrapolated Raman and Raman optical activity (ROA) spectra of large molecules (vide infra).