Non-convergence of iterative solution of linear equations ("lkain: not converged")


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Hi everyone,

I am trying to perform an NMR shielding calculation but have encountered a non-convergence in the linear equation solver.

There seems to be little documentation of options to improve convergence, nor has anyone really encountered this before in the previous threads.

Can anyone offer any advice as to what parameters can be tuned? As nothing stands out in the source code.

(I can send my input to anyone if interested, but it is massive so I've avoided listing it here. I'm testing the NMR shielding for molecular vs qm/mm embedded systems, of different sizes, and so there are alot of lines in the input file from all the point charges)

Thanks in advance,

Andy