[DFTB-Plus-User] Queries about the SCCTolerance and MaxSCCIterations

[rsaha at icredd.hokudai.ac.jp]

Hello All,

I am using DFTB+ for a few months. I am using this software optimisation 
as well as MD. I have a few queries about the SCC iterations.

For optimisation, I have used SCCTolerance = 1e-6 and MaxSCCIterations = 
500. The geometry and SCC converged well for optimisation process.
For MD, these same parameters have been used and it worked well this far,
 though the time taken is very large. Recently, I am facing a problem in 
generating the tragectory. The SCC is not converging after few steps in 
the MD. 

After searching in the web, I found (https://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/2020/003310.html)
 a solution as lowering the SCCTolerance and adding ForceEvaluation. 
Currently, I am doing MD with, SCCTolerance = 1e-3 and MaxSCCIterations 
= 200 and also ForceEvaluation = Dynamics (in Driver section).

(1) I do not know, is this parameters are correct to use for MD? 
(2) What values of the SCCTolerance and MaxSCCIterations can be used? 
How much lower values can be used? How to get the idea of the 
SCCTolerance and MaxSCCIterations that will be better for MD (or 
optimisation)?

If anyone can comment or have any suggestion, please write to me. I will 
be happy to hear from you.

Thank you for your time.

Regards
Ranajit