Hello,

I have a similar problem with the triplet T1 excited state energy optimization for uranyl-triauqa-sulphate complex within the DFT/B3LYP/def-SVP (Turbomole V6.5).

I started the calculation from the optimal geometry for the ground S0 state. But soon after the optimalization (26 steps in steepest descent algorithm with dqmax=0.1) I have get the GEO_OPT_FAILED result since the last point has a

" Reference state is unstable

egrad ended abnormally

"

error message on its end.

My supervisor (who doesn't supervise particularly this project, I am playing with uranyl more like on my own) told me, that it is obvious that the DFT converged to excited state, so I should swap MOs (or KS orbitals to be accurate).

But I am not sure if just reordering the MOs from the failed calculation (or from the last point of the optimization trajectory where it still worked) would work ... and which one of the virtuals I should take instead of the currect HOMO (or HOMO-1, HOMO-2, ?). Since the resulting occupation is 2222...2 00..0. Is it possible to do the swap before the DFT-self-consistent equations are being solved?

I have found elsewhere (

https://groups.google.com/forum/#!topic/newtonx/G7DkofJR5YM) answer (for completely different molecule and in combination with the dynamics, but the problem might be the same) that

- Unrestricted KS

(and/or) - Fractional occupation (in particular, temperature smearing)

would work.

Since I am interested in temperature smearing of KS occupation numers also with the perspective to better model 298K temperature effects, I will try the last one.

I will try both the post-DFT reordering