1.Modified Lorentz : reference
A. Deinega and S. John, “Effective optical response of silicon to sunlight in the finite-difference time-domain method,” Opt. Lett. 37, 112-114 (2012)
http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-37-1-112
Electromagnetic Template Library (EMTL)
http://fdtd.kintechlab.com/en/fitting
2. RefFIT
http://optics.unige.ch/alexey/reffit.html