A comparative study of the vibrational corrections for the dynamic electric properties of the LiF molecule using numerical and perturbation methods

In this work we report results of CPHF calculations, including vibrational corrections, for the dynamic polarizability and first hyperpolarizability of the LiF molecule. Vibrational corrections were computed through the Numerov-Cooley and perturbation-theoretic methods. Comparison between the results obtained using both methods shows that first-order perturbation-theoretic provides a good approximation for the zpva contribution. The double-harmonic-oscillator approximation is reliable for the pv contributions of αzz, βxxz and βzxx, while [μα]0 + [μ3]I is a good approximation for βzzz. CCSD(T) results obtained for the pv contribution show that the electron correlation effects are small for the polarizability but significant for the first hyperpolarizability.