The IterationControlParameters actually do not influence the self-consistent cycle in any way. Perhaps a more proper name for it should have been "convergence criterion parameters", because that's what it's all about: determining the criterion for when the scf cycle should be considered to have converged. The default TotalEnergy criterion is, in basically all cases, most suitable, while you can choose a higher threshold than default for testing purposes (or lower, to make sure you have good quality results). Finally it's sometimes convenient to increase the maximum number of steps if you expect that you need more, to avoid having to restart after 100 steps.