A K-dependent adiabatic approximation to the Renner–Teller effect for triatomic molecules.

A K-dependent adiabatic approach is suggested to study the Renner–Teller effect in triatomic molecules using a two-dimensional Hilbert space approximation in the electronic degree of freedom. The theory is developed in hyperspherical coordinates, and approximately includes the electronic spin–orbit interaction. The adiabatic Hamiltonians are expressed in terms of a K-dependent effective potential energy surface. Eigenpairs are calculated by solving the time-independent Schro¨dinger equation, which is represented in a mixed grid/basis set. The method is applied to the A˜←X˜ band system of bromomethylene (H/DCBr). The results obtained show that the Renner–Teller effect in this molecule is pronounced, particularly in the excited A˜ [sup 1]A[sup ″] state. The results are compared to recent experimental measurements and good agreement is found. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]