Accurate Potential-Energy Function for Diatomic Molecules

A three‐parameter potential‐energy function for diatomic molecules proposed by Varshni and Shukla, has been modified to improve its accuracy. The modified function is ${\mathrm{U=D}}_e{\text{{1−(r}}_e\mathrm{/r)}\exp {\mathrm{[-a(r}}^p{\mathrm{-r}}_e^p{\mathrm{)]\}}}^2$ , where D_e is the molecular dissociation energy, r_e is the equilibrium internuclear distance, and $\text{p=2+}\frac{1}{4}{\mathrm{(\Delta }}^{\frac{1}{2}}{\text{−4)(Δ}}^{\frac{1}{2}}{\text{−2)/(Δ}}^{\frac{1}{2}}\text{−1)}$ , where Δ=½k_er_e²/D_e, k_e being the force constant. This function appears to be more accurate than previously proposed three‐parameter functions.