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Re^2: Energy rises and oscillate at the end of optimization

Oleg Levitskiy

Thank you for reply, Pavlo!
I've run a job with parameters you had suggested just now. I'll write here about the results as soon as I obtain them.
Regarding the starting geometry... It was tightly optimized in gas phase first (in QC progam "PRIRODA" which I usually use for gas-phase calculations). After that I've tryed to optimize gas-phased optimized geometry in Firefly with PCM model applyed. At initial steps the process proceeded normally with energy decreasing from step to step. But when gradient became small the problem with convergence appears.
I choose PBE as functional because it's a default functional in "PRIRODA". May be it's objectively not  the best option but I haven't ever noted any unrealistic results.
Why now I'm truying to apply a solvent  model? Because I've recently started the work on modeling reactions of charged nucleophilic species. Without accounting for solvent affects I've obtained no barrier during the PES scan for nucleophilic addition reaction.
Sorry for long talking and thank you again for your help!


On Thu Sep 11 '14 5:18am, Pavlo Solntsev wrote
>I would recommend you try these parameters first:
> $contrl scftyp=rhf dfttyp=pbe96
> runtyp=OPTIMIZE icharg=-1 nprint=-5
> maxit=100 ICUT=11      ITOL=30 NZVAR=168 $end
> $system mwords=100 $end
> $SCF DIRSCF=.true. maxdii=20 $end
> $guess guess=moread $end
> $ZMAT DLC=.T. AUTO=.T.$end
> $p2p p2p=.t. dlb=.t. $end
> $basis gbasis=TZV $end
> $PCM PCMTYP=DPCM SOLVNT=input RSOLV=2.155 EPS=35.688 EPSINF=1.806874 $END
> $PCMCAV RIN(58)=1.956 $END

>Before apply a solvent correction, you need to optimize the geometry in a gas phase. Make sure you use a right functional. I am skeptical about pbe96. Do not expect very tight gradient for the geometry with the solvent correction. Usually 10^-4 is ok.

>On Tue Sep 9 '14 3:30pm, Oleg Levitskiy wrote
>>Dear Firefly Users,
>>I've tryed to perform an optimization of anionic complex of Ni (DFT/PBE96, PCM) and faced a problem with convergence. Energy has unexpectedly risen and fluctuate spontaneousely from step to step. I've tryed to increase accuracy (ICUT, ITOL values and also DLCTOL and ORTTOL), to change optimization method (GDIIS, NR), to perform optimization in cartesian or delocalized coordinates, but the result was similar in all cases. Could you advise me something else to solve this problem.
>>The beginning of my input is following:

>> $contrl scftyp=rhf dfttyp=pbe96
>>runtyp=OPTIMIZE icharg=-1 nprint=-5
>>maxit=100 ICUT=20 ITOL=30 NZVAR=168 $end
>> $system kdiag=-1 mwords=100 $end
>> $SCF DIRSCF=.true. maxdii=20 $end
>> $guess guess=moread $end
>> $STATPT method=NR $end
>>DLCTOL=1D-7 ORTTOL=1D-7 $end
>> $INTGRL PACKAO=.true. $end
>> $p2p p2p=.t. dlb=.t. $end
>> $basis gbasis=TZV $end
>> $PCM PCMTYP=DPCM SOLVNT=input RSOLV=2.155 EPS=35.688 EPSINF=1.806874 $END
>> $PCMCAV RIN(58)=1.956 $END

>>Typical out-file is attached.

>>Thank you,


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