Table 2.
Overview of Programs for Computing Collision Cross Sections of Gas-Phase Ions.
| Computation Suite | Method | Scattering Type | Explicit Trajectories | Temperature/Charge State-Dependent | 3D Geometry-Dependent | Buffer gases |
|---|---|---|---|---|---|---|
| MOBCAL | PA | - | - | − / − | - | He |
| [89] | PA* | - | - | − / − | + | He |
| EHSS | elastic | + | − / − | + | He | |
| TM | elastic | + | + / + | + | He | |
| WebPSA [95] | PSA* | - | - | + / + | + | He/N2 |
| LCPA [96] | LCPA | - | - | + / + | + | He/N2 |
| Sigma [97], | PA* | - | - | − / − | + | He |
| CCSCalc [98], | ||||||
| IMPACT [21] | ||||||
| EHSSRot [99] | EHSS | elastic | + | + / − | + | He |
| IMoS [100] | PA | - | - | − / − | - | He/N2/ |
| (D)TM | elastic (inelastic) | + | + / + | + | Ar/CO2/air | |
| EHSS (TDHSS) | elastic (inelastic) | + | + / + | + | ||
| Collidoscope [86], HPCCS [101], MobCal-MPI [102] | TM | elastic | + | + / + | + | He/N2 |
Features present (+) or absent (−) in various CCS calculation tools. Methods in bold type use 2-dimensional projections rather than explicit 3-dimensional scattering for CCS computations. Asterisks (*) indicate that a geometry-dependent “shape factor” is used to partially account for 3-dimensional scattering. PA = Projection Approximation, EHSS = Exact Hard Spheres Scattering, PSA = Projected Superposition Approximation, LCPA = Local Collision Probability Approximation, TM = Trajectory Method, D indicates inclusion of diffuse scattering (see ref. [52]). Adapted with permission from Ewing, S.A., Donor, M.T., Wilson, J.W., Prell, J.S., Collidoscope: An Improved Tool for Computing Collisional Cross-Sections by the Trajectory Method, Journal of the American Society for Mass Spectrometry 28 (2017) 587–596, copyright 2017 American Society for Mass Spectrometry.