ქიმიის ტერმინთა განმარტებითი ლექსიკონი

A force field expressed in terms of 3N - 6 basis coordinates:

Where f_ij (or F_ij) are force constants and the basis coordinates S (or sometimes s) may be internal symmetry coordinates, local symmetry coordinates or any others suitable to the problem, but the number of the coordinates has to be reduced to 3N - 6 (3N - 5 for linear molecules), N being the number of atoms in the molecule.