The Ritz program for assigning rotational and rovibrational transitions in asymmetric-top molecules

The Ritz program is a user-interactive software package that simulates and enables the assignment of spectra of asymmetric top molecules, up to high rotational quantum numbers. The set of initial assignments can be extended using generated predictions for line positions. The graphical interface of the program handles wide spectral features corresponding to overlapped lines by fitting the expected number of profiles to the experimental contour. Features of the program allow for the detection and examination of Coriolis interactions. Initially designed to work for methanol and its isotopologues, the program has been modified to assign the spectra of cyanamide, hydrazine, acetaldehyde, and oxetane. An extension of the program, LaseRitz, has been developed for the assignment and prediction of optically pumped far-infrared laser transitions. Our paper presents a description of how the Ritz program works and provides an overview of studies carried-out using this software.