SUSPRE (Surrey University Sputter Profile From Energy Deposition) was originally commissioned by VG Ionex in the late 1980s to help interpret dynamic SIMS spectra. It is based around the Projected Range Algorithm – formulated by Jochen Biersack – as a solution to the Boltzmann Transport Equation. It has been demonstrated to be as accurate as SRIM for determining ion Range parameters but is a much faster, only taking seconds to produce a result and can be used as a handy calculator
The basic formulation of SUSPRE can be found in the reference below: Webb, R. P. & Wilson, I. H. An Extension to the Projected Range Algorythm (PRAL) to give Energy Deposition Profiles. in Proc. 2nd Int. Conf. Simulation of Semiconductor Devices and Processes, (1986). The text of this reference can be found here.