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Re: Problem to optimize minimum energy conical intersection (MECI) for SHIFT less than 0.005

Alex Granovsky

Dear Evgeniy,

PHASE2 restart normally requires hessian from a previous run.
In addition, I'd suggest using small trmax and dxmax (these are
variables of $statpt group), normally ten times smaller than
their default values. Tighter cutoffs throughout are necessary.
Finally, are you using DLCs or cartesians?

Kind regards,

On Wed Sep 7 '16 6:09pm, GrEv wrote

>I am attempting to find a MECI between S0 and S1 using SA-CASSCF(12,11). An attempt to localize MECI starting directly with SHIFT=0.0001 (default) failed. I decided then to search in a step-wise fashion, starting with SHIFT=0.01 and then decreasing it after every successful search. However, I couldn't optimize MECI for SHIFT less than 0.005. I wonder what the problem could be? I am using the following options for the search:

>$CONIC SHIFT=0.001 SHIFT0=0.001 STAGE2=.t. LSTART=0.8492530370 $END

>(LSTART is from the previous serach with SHIFT=0.005)

>$STATPT OPTTOL=0.00010 NSTEP=500 method=conic $END


>Best reagrds,

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