Number of ionic steps in plane wave DFT What is the significance of increasing (and decreasing) the number of ionic relaxation steps in a plane wave DFT calculation?
 A: Assuming the question is about the computation parameter (Maximum number of ironic steps):
Maximum number of ironic steps is the cap where the calculation will drop regardless if its converged.
It's a good idea to limit the maximum number of ironic steps (I personally use 100), so that you can see what's happening during the calculation and adjust parameters accordingly, then resumes the calculation from where it's dropped.
If you do not limit the number of ironic steps, and the structure would not have converged anyway, the calculation will run forever.
Assuming the question is about the computation results.
In ionic relaxation iterations, the ionic SC loop will continue to run unless either the followings is satisfied.

*

*Convergence criteria is satisfied.

*Maximum number the ironic steps is reached.

So basically the harder the convergence criteria is, the more number the ironic steps will it take to converge. If the calculation does not converge within the maximum steps, the iteration will stop there.
