The default settings of QCxMS provide a good starting point for the calculations. However, if more control for Running QCxMS is needed, example input files for each run type can be found below.
EI - positive Ion Electron Ionization¶
ei xtb ntraj xxx tmax xxx
DEA - negative Ion Electron Ionization¶
dea scan 1 upper 15 lower 0 <functional> <basis>
Instead of the IEE distribution, the excess energy is scanned by switching on the scan keyword, with upper/lower bounds in eV. The negative ion mode is enabled with the the xtb method or the orca program for DFT methods. The ma-def2-SVP/ma-def2-TZVP basis sets are recommended for anion calculations. The xtb negative ion simulations are not recommended for production level for accuracy reasons.
CID - positive Ion Collision Induced Dissociation¶
cid xtb2 eimpact 60 lchamb 0.25 fullauto
The run-type must explicitly be defined so the program knows how to handle the number of collisions. For the general activation method, use the fullauto command. For the forced activation run-type, the number of collisions are set by using collno x to set all collisions (including fragment-gas collisions (fgc)). For setting ONLY mol. ion-gas collisions, use maxcoll x.