Computing ro‐vibrational spectra of van der Waals molecules

This article reviews methods for computing ro‐vibrational spectra of van der Waals molecules. Due to the presence of large‐amplitude motion, calculations often play an important role in assigning and understanding the spectra of van der Waals molecules. Fortunately, it is possible to make usefully accurate calculations because important parts of the spectrum can be understood by doing calculations that omit the intramolecular coordinates. In this article, we present new ideas for deriving kinetic energy operators and discuss choosing basis functions and doing the matrix–vector products that are required to obtain a spectrum using the Lanczos algorithm.