Assessing Collision Cross Section Calculations Using MobCal-MPI with a Variety of Commonly Used Computational Methods

Abstract Structural studies with ion mobility require an accurate methodology to bridge theoretical modelling of chemical structure with experimental determination of an ion’s collision cross section (CCS). The parallelized MobCal-MPI package enables rapid and accurate evaluation of CCSs that are applicable to several chemical classes, but was only assessed for accuracy using a single model chemistry: B3LYP-D3/6-31++G(d,p). Thus, the performance of MobCal-MPI was validated across 25 different model chemistries, which encompass Hartree-Fock and three common DFT functionals (B3LYP-D3, ωB97X-D, and M06-2X-D3) using six different basis sets (6-31 G, 6-31 G(d,p), 6-31++G(d,p), def2-SVP, def2-TZVP, and def2-TZVPP), as well as PM7. Performance assessment was accomplished using geometries generated from a set of 50 structurally diverse molecules (238 total isomers) at each level of theory. MobCal-MPI produces CCSs that correlate with experimental values with