A variational parameter used as a multiplier of each nuclear Cartesian and electronic coordinate chosen to minimize the variational integral and to make a trial variation function to satisfy the virial theorem. In practical calculations, the numeral factor to scale computed values, e.g. vibrational frequencies, to those found in experiments.
PAC, 1999, 71, 1919. 'Glossary of terms used in theoretical organic chemistry' on page 1961 (https://doi.org/10.1351/pac199971101919)