Knowledge Bank

Due to the large value of the coefficient $k133$ appearing in the cubic potential, the perturbation calculation of energy levels of $co2$ exhibits a good $convergence1$ only for very small values of the quantum number $v3$. This situation can be improved by using Effective Normal Coordinates $(ENC)2$ which depend upon the value of $v3$. We present a second order calculation of the potential from the experimental energy levels, using a ENC inversion technique recently $developped3$. The results will be compared with those obtained by other methods.