I am using Morse potential to calculate the spectroscopic constants of a diatomic molecule. So far I was able to calculate $R_e$, $\omega_e$, $\omega_ex_e$, $B_e$ but wasn't able to calculate $\omega_ey_e$ and $\omega_ez_e$. Does anyone have any idea how to calculate these two constants. I was searching in several textbooks for equations that I can use to calculate them using the Morse potential but I wasn't successful! Any help is really appreciated.