Calculation of the normal modes of vibrations of a molecule or crystal under the assumptions that the potential energy is harmonic and the displacements from equilibrium are infinitesimal.
See also: normal coordinate, vibrational eigenvector
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 756 (https://doi.org/10.1515/pac-2019-0203)