The vibrational spectrum of a system may be described in terms of the equilibrium configuration. A band observed in the infrared region may be thought of as a change in dipole moment which can be associated with the displacement of a group of atoms from their position in the equilibrium configuration, and a band in the Raman spectrum may be thought of as a change in polarizability which can also be described as the displacement of a group of atoms from their equilibrium position. In these terms, then, one speaks of the C–H stretching fundamental or the H−C—C deformation. However, these displacements are determined only if their equilibrium positions are known, as well as the totality of equilibrium positions that define the equilibrium configuration or the structure of the system.
KeywordsIrreducible Representation Fundamental Mode Point Group Binary Operation Equilibrium Configuration
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