Welcome to the MARVEL website!
What is MARVEL?
The acronym MARVEL stands for Measured Active Rotational-Vibrational Energy Levels. MARVEL is based on the concept of spectroscopic networks. The code MARVEL is written in C++ and it is designed for critically evaluating and validating experimental transition wavenumbers and uncertainties collected from the literature as well as for inverting, in a highly efficient way, the wavenumber information in order to obtain the best possible energy levels with attached uncertainties. MARVEL simultaneously processes all the available assigned experimental lines and determines the associated energy levels for the chosen molecule. MARVEL can invert a 100,000 by 100,000 matrix in a fraction of a second. While the energy levels obtained could be called empirical, in order to emphasize the process they were derived from the evaluated and validated energy levels are usually called MARVEL energy levels.
The MARVEL Process
Gathering experimental data
All high-resolution experimental transitions data gathered from the literature can be used within MARVEL. It is best to give each data source a tag (metadata), perhaps based on the year of publication and letters from the names of the author(s). In order to be used in MARVEL each transition has to have an initial non-zero uncertainty and a unique label, describing the lower and the upper energy levels. Ideally, the uncertainties and the labels are taken directly from the source but in several cases uncertainties have to be guessed.
Cleaning the data
For each molecule a test facility must be developed to check all experimental transitions for uniqueness, including uniqueness of the label (note that it is perfectly acceptable to use labels corresponding to a redundant set of quantum numbers and symmetry information; in fact, for symmetric tops this seems to be the preferred route), to avoid duplicating the same datum and for consistency. Conflicts arising from the use of experimental data from multiple sources should be identified and corrected.
Execution of MARVEL
During the execution of MARVEL the uncertainties of the lines measured are adjusted via a robust reweighting technique until a self-consistent set of experimental uncertainties are obtained. The energy levels obtained from this self-consistent database are the ones called MARVEL energy levels. The MARVEL energy levels can be used to obtain experimental-quality transitions using the selection rules appropriate for the given molecule.