Knowledge Bank

A new method for refining potential energy surfaces in triatomic molecules via nonlinear least squares has been applied to water in its ground electronic state. Experimental rovibrational energy levels with and band origins observed below $20,000cm-1$ have been used to improve upon Jensen's $surface1$ in a fully variational calculation. The new surface does a much better job at reproducing rotational energies with large values of $KA$ than those available in the literature, while at the same time maintaining physically meaningful values for all of the parameters involved. The results should be of general interest, however they will be discussed in terms of their relavence to searches for spectral lines in the microwave and infrared. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ Per Jensen, J. Mol. Spectrosc. 133, 438-460 (1989).