Second hyperpolarizabilities of 1-center radicals

We study the second hyperpolarizabilities ( γ) for 1-center radicals, i.e., BH3−, CH3 and NH3+. It is found that magnitudes of γ( ¦γ¦) of the radicals are sensitively influenced by features of each charged state. It is also found that electron-correlation dependence of γ can be related to the resonance structure contributing to the ground state of the molecules