SPECTRE

SPECTRE is a program for calculating spectroscopic and magnetic single-ion properties of rare-earth ions in crystals. The calculation employs intermediate coupling basis states, and allows mixing of all terms within the fⁿ configuration. The program includes a facility for fitting crystal field parameters to sets of energy levels and transition intensities for one or more ions.

A full description of the software is given in the user guide

Further information can be obtained from Andrew Boothroyd