Spectroscopy

Quantum mechanics

Raman spectroscopy

Chemical physics

Pure mathematics

Delocalized electron

Field (mathematics)

Polyatomic ion

Operating system

Vibration

Molecule

Computer science

Physics

Organic chemistry

Mathematics

Molecular physics

Normal mode

Hot band

Computational chemistry

Chemistry

Molecular vibration

Mode (computer interface)

The Journal of Physical Chemistry A

This Feature Article starts highlighting some recent experimental and theoretical advances in the field of IR and Raman spectroscopy, giving a taste of the breadth and dynamics of this striving field. The local mode theory is then reviewed, showing how local vibrational modes are derived from fundamental normal modes. New features are introduced that add to current theoretical efforts: (i) a unique measure of bond strength based on local mode force constants ranging from bonding in single molecules in different environments to bonding in periodic systems and crystals and (ii) a new way to interpret vibrational spectra by pinpointing and probing interactions between particular bond stretching contributions to the normal modes. All of this represents a means to work around the very nature of normal modes, namely that the vibrational motions in polyatomic molecules are delocalized. Three current focus points of the local mode analysis are reported, demonstrating how the local mode analysis extracts important information hidden in vibrational spectroscopy data supporting current experiments: (i) metal-ligand bonding in heme proteins, such as myoglobin and neuroglobin; (ii) disentanglement of DNA normal modes; and (iii) hydrogen bonding in water clusters and ice. Finally, the use of the local mode analysis by other research groups is summarized. Our vision is that in the future local mode analysis will be routinely applied by the community and that this Feature Article serves as an incubator for future collaborations between experiment and theory.

The Local Vibrational Mode Theory and Its Place in the Vibrational Spectroscopy Arena