Calculation of Vibrational Spectra of Large Molecules from Their Fragments

Abstract

Vibrational spectroscopies proved extremely useful to study a broad range of molecules, including their structures and interactions. Additional structural sensitivity is provided by polarized techniques measuring different absorption or scattering of left- and right circularly polarized light. The vibrational optical activity (VOA) methods include Raman optical activity (ROA) and vibrational circular dichroism (VCD). Interpretation of the spectra, however, is largely dependent on time-consuming quantum-chemical simulations limited by molecular size. To be able to handle at a reasonable precision large molecules, such as biologically relevant systems, we developed a simplified method of transfer of vibrational atomic properties from smaller fragments to the system of interest. The method found many successful applications in the past, including spectra of proteins and nucleic acids, and appears useful also in connection with the multi-level computational techniques in the foreseeable future. In this chapter, we discuss the theoretical whereabouts of the transfer method and its related computational algorithms and describe typical applications to large molecules.