New potential energy surfaces for the and states of CH

Abstract

We report new ab initio calculations of the three-dimensional potential energy surfaces for the Renner-effect coupled ground electronic state and first excited electronic state of the CH molecule. We also make an ab initio calculation of the spin–orbit coupling surface between these states. Using these ab initio surfaces in our computer program RENNER, we calculate term values and absorption line intensities, and compare with recently observed high resolution spectra. Adjusting two parameters in the potential surfaces we are able to achieve satisfactory agreement with the experimental results except for those that involve the state (, l = 1) vibronic level. The implication of this disagreement is discussed.