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Re^3: Optimization of conical intersection with penalty function method: how to control the gap?

Alex Granovsky

Dear Evgeniy,

SHIFT0 and SHIFT variables are primary used by Lagrange multiplier-
based code.

SHIFT can be used with penalty function based code but has very
little impact on the energy gap when gap is large and shift
is small. It is intended to trace rather large differences between
states like 0.1 or 0.05 Hartree.

Kind regards,

On Sat Oct 22 '16 7:39pm, GrEv wrote
>Dear Alex,

>Thanks very much for your reply.
>Just a curios question, what does the SHIFT option do?

>Best regards,

>On Sat Oct 22 '16 6:00pm, Alex Granovsky wrote
>>Dear Evgeniy,

>>there is no direct control over the energy gap for penalty-based CoIn
>>optimization procedures. The gap can be controlled indirectly using
>>parameters defining a penalty function. The larger is the "strength"
>>of penalty function the smaller will be the gap. With Firefly, the
>>strength is controlled by the parameter B of $mcaver group.

>>Kind regards,
>>On Sat Oct 22 '16 11:50am, GrEv wrote

>>>I am doing optimization of the minimum energy conical intersection using the penalty function method, with the following input (from the manual, p. 176) :

>>>$STATPT OPTTOL=0.00005 NSTEP=500 method=qa trmax=0.05 dxmax=0.05
>>> HSSEND=.f. $END

>>>Using this input I found a conical intersection (CoIn), with the final gap between the states of 0.003. I'd like however to have a smaller gap, let's say 0.0001. How this could be done. I've tried to use the SHIFT option in $MCAVER, setting SHIFT=0.0001. It however didn't do the job. I got a CoIn with almost the same gap as before.
>>>Many thanks!


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