"On the art of computing the IR spectra of molecules in condensed phase. "Matthias Schmitz and Paul Tavan
In: Modern methods for theoretical physical chemistry of biopolymers.E.B. Starikov, S. Tanaka, J.P. Lewis (Eds.).Chapter 8, pp. 157-177 (Elsevier, Amsterdam, 2006).
Infrared (IR) spectroscopy is a most important technique for identifying compounds and
monitoring their reactions in (bio-)chemistry. Usually spectra are obtained from condensed
phase samples containing molecules embedded in solvents of varying polarity or in complex
and polar protein environments. Upon transfer from the gas phase to the condensed phase,
the vibrational frequencies may become sizeably shifted and the lines inhomogeneuosly broadened.
For molecules comprising up to about 100 atoms accurate computations of their gas-phase IR
spectra were enabled by the development and wide-spread accessibility of density functional
theory (DFT) about one decade ago. Concerning molecules in condensed phase, however, the art
of accurately computing the IR spectra is an ongoing development, whose computational basis is
provided by hybrid methods combining DFT descriptions of molecules with molecular mechanics (MM)
models of their condensed phase environment. Here we review the involved physics, the available
computational procedures, the achievements, and the perspectives of this DFT/MM based development,
which promises to provide detailed insights into the structural dynamics of condensed phase
(bio-)chemical reactions by quantitative descriptions of corresponding IR spectra.
BMO authors (in alphabetic order):
QM/MM hybrid descriptions of solutes in complex solvents