When using a given basis set, both energy and this quantity are multiplied by a dimensionless scaling factor usually close to 1 to account for a term called ZPVE. For a transition state, this quantity takes on an imaginary (15[1])value (-5[1])since it corresponds to a negative eigenvalue of the mass-weighted (15[1])Hessian (15[1])of a (-5[1])Born-Oppenheimer surface. Olfactory receptors identify molecules by their value for this quantity, according to the controversial (*) "swipe card model." Heavy isotopologues (-5[1])have lowered values of this quantity, lowering the rate constant in the kinetic isotope (-5[1])effect. (-5[3])For a covalent bond modeled as a Hookean spring, this quantity is (read slowly) one over two (-5[1])pi times the square root of force constant over (-5[1])reduced (10[1])mass. For (10[1])10 points, name this quantity that describes (10[1])the rate at which an atom in (-5[1])a (10[4])molecule oscillates, (10[1])measured (10[1])in (10[12]0[1])hertz. ■END■