Knowledge Bank

The nonrigid bender Hamiltonian for the triatomic molecule was developed by Hoy and $Bunker1$ and used by these authors to fit experimental data for the bent $H2O$ molecule. In the course of using this Hamiltonian to calculate the rotation-vibration energy levels of $CH22,3$ it was found that for a quasilinear or linear molecule it is necessary to include some previously neglected terms and Co group some of the terms in a special way before attempting to calculate the eigen-values. These modifications will be discussed. The 61 available experimental transition frequencies for the three methylene isotopes $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH2,13CH2$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CD2$ in the $X~3B1$ ground state have been simultaneously fitted using the non-rigid bender model, a refined potential surface for this electronic state being obtained. The results of the fit will be presented together with predictions of the stretching frequencies, which have not been observed $experimentally.1$A.R. Hoy and P.R. Bunker, J. Mol. Spectrosc. 52, 439 (1974); ibid. 74, 1 (1979). $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$Per Jensen, P.R. Bunker and A.R, Hoy, J. Chem. Phys. 77, 5370 (1982). $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$P.R. Bunker and Per Jensen J. Chem. Phys., to be published.