Non-converged second singlet excited state

[mimonge]

We are optimizing different substituted  pyridine in the ground and lowest singlet excited states. For that, we freeze an angle and we  optimize the rest of the molecule in the corresponding state. We want to optimize the first two singlet excited states S1 and S2. For doing that we use SVP basis sets  and b3-lyp functional with egrad module writing in control file:

$scfinstab rpas
$soes
$a n
$exopt n

Where n it is 1 or 2

While the first singlet S1 converges for all frozen angles, our problem it is that it does not converge for the second S2 excitation singlet even after more than 100 cycles. Would you have any suggestion for that?

Thanks in advance
Miguel

[e.berardo]

Hi Miguel,
I am a beginner with Turbomole, but I will try to help you with what I know....
Did you check the gradient "grep cycle gradient"? Is it constantly decreasing or it is going up and down?
What is the lowest excitation in job.last?
If the gradient is acting weirdly, or the excitation is too low (order of 10-1 eV) I would assume that you are going to end up in a non-real state, usually caused by a conical intersection and you cannot optimize your excited state.
If not, then let it go on. Increase the n* of optimization steps and see what happens.

cheers,
Enrico

[Arnim]

Additionally to Enrico's suggestions, you could maybe also check, if the third or fourth excited state comes down and mixes with the second.
The settings would be something like this:
$soes
 a 4
$exopt 2

Cheers,

Arnim

[mimonge]

Dear Enrico and Arnim,
thank you very much for your suggestions.

Best Regards
Miguel