force constants
The coefficients in an expansion of the @I03130@ potential function in terms of a definite set of coordinates, the values of which define the deformation of the molecule away from its equilibrium configuration. In order to define force constants, one has to indicate both the definition of each coordinate and the expansion of the potential.
PAC, 1978, 50, 1707. (Definition and Symbolism of Molecular Force Constants) on page 1709 [Terms] [Paper]