LEVEL16 is R.J. Le Roy's program for calculating the eigenvalues of bound and quasibound levels of any smooth one-dimensional or radial potential, together with (as desired) expectation values and centrifugal distortion constants for specified levels, and Franck-Condon factors or matrix elements of specified powers of a chosen distance variable (and hence of quantities expanded as power series in this variable) or of a user-specified radial function defined by interpolating over a set of read-in points. Such off-diagonal matrix elements may couple levels of the same potential or levels of two different potentials, subject to rotational selection rules specified by the user's input data file. A full description of the most recent version of this code has been published in J. Quant. Spectrosc. Radiat. Transfer 186, 167 (2016), which is available at http://dx.doi.org/10.1016/j.jqsrt.2016.05.028, while the corresponding source code and detailed Program Manual are available as Supplementary "Application" files at that www link. All future citations regarding use of this code should refer to this Journal Article.
Note that the order in which some input parameters are read has been modified (hopefully improved) from that in earlier versions, so previous users are advised to read the program manual carefully when setting up their input data files. This new version uses the 2010 values of ħ, and its atomic masses subroutine incorporates the 2012 version of the atomic mass table.