Converge, dammit!

One of the biggest irritations in time dependent DFT calculations is getting your functionals to converge. And a certain large molecule that I’m trying to work some calculations on is just being a little carbonaceous bitch. I’ve run the calculation three times now and it’s still giving me “SCF failed to converge”.

Ok. One more try. I resubmitted the file (after tinkering with it) a couple of hours ago and the output’s looking a little wobbly, but otherwise ok so far. Fingers crossed. I feel like an engineer sometimes actually — some of these things are a case of finding the right values by direct experimentation, or in simpler terms, screwing around with it until it works.

Anyway, here’s hoping it works this time… Converge! Converge, I say!



Current DIIS subspace size = 15

REM_GRID_RESTART_DIIS = 0
   50   -1262.0106527154      9.86E-04  00000    Convergence failure
 Q-Chem fatal error occurred in module scfman.C, line 1724:
 SCF failed to converge

(Incidentally, this is from the first of the output files… If after several attempts, I was still only down as far as 10^-4, I’d have gone and kicked it by now. And it’s not a good idea to kick a supercomputer…)