Knowledge Bank

We took the potential energy surface for the ground electronic state of $NO2$ constructed by Tashkun and $Jensena$ using the MORBID Hamiltonian and computer program. We wished to fit this experimental date using the exact kinetic energy (EKE) operator. Initially, EKE calculations were not not possible due to the presence of holes in the surface. A better starting point for the fit was constructed using the method in Polyansky $etalb$ whereby MORBID and EKE calculations are combined. We then improved the surface by fitting it to available experimental data using an iterative least-squares fitting procedure. In the low-energy region ( $cm-1$) the fitting was successful. Above apporximately $10,000cm-1$ the higher electronic state begins to peturb the vibrational energy levels of the ground state. We were unable to fit the surface well to the experimental date above $10,000cm-1$. We aim to provide a surface which will give accurate rovibrational levels of $NO2$.