An automated branch-assignment algorithm for rovibrational spectra of asymmetric-top molecules

There are several methods for isolating a P, Q, or R branch from the rest of the unassigned rovibrational spectrum of an asymmetric-top molecule. But at the moment, to our knowledge, once the branch has been isolated, there is no automated procedure for its assignment. Here, we present a simple semi-empirical algorithm which has proved successful in computer experiments on both S(CN)₂ (a near prolate rotor) and C₃H₆O (a near oblate rotor.) The limits to the applicability of this method are discussed.