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Re^6: A problem in PCM/TDDFT (B3LYP1) Calculation

Arshad Mehmood

Thank you very much for your reply.
I did the same during optimization but Firefly ended with error.
I have one question. I am confused about my calculations after our discussion. If molecular viewer like Mercury and Chemcraft etc exhibit the molecule using output file of Gaussian or firefly as is shown by XRD data then still our calculations i.e. optimization coordinates are doubtful? Because the output file of Gaussian 09 and Firfly shows the same molecule with slightly different angles, torsion angles and bond lengths.
The MM2 minimization also demonstrates nearly same coordinates obtained from Gaussian 09. Are my optimization calculations still doubtful?

I really apologize for the inconvenience caused by my frequent emails.


On Sun Dec 30 '12 6:56pm, sanya wrote
>Actually, you cannot use *.cif file directly to generate input for any quantum chemistry program, because the coordinates in *.cif are fractional rather than cartesian. The input file thus created contains incorrect coordinates, and the optimization, if ever, definitely ends in the wrong minimum.
>So, you should first convert *.cif into, say, *.pdb using Mercury, next, open in with Chemcraft or MaSK and create FireFly or Gaussian input. Can you show me the *.cif file you used?

>On Sun Dec 30 '12 4:13pm, Arshad Mehmood wrote
>>I am using Mercury CSD, Chemcraft and MaSK as Molecular Viewer.
>>The gemoetry of molecule was not drawn using any Chemical drawing software. I used .cif file. I first tried to optimize using Firefly but it failed to locate stationary point and SCF was not converged.


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