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Re^2: How do I get a better initial guess (SnI3)?

David Shobe


Follow-up question: Will $contrl d5=.t. $end affect the energy or other properties that are calculated?  In particular, will I have to recalculate SnI4 and I (atom) with $contrl d5=.t. $end to get an accurate bond dissociation enthalpy>


On Thu Jan 25 '18 9:42am, Alex Granovsky wrote

>First, you need to add $contrl d5=.t. $end option to your input file.
>Second, you need to use either $contrl inttyp=hondo $end or direct scf
>with fastints code ($scf dirscf=.t. $end, $contrl fstint=.t. $end ).

>Hope this helps.

>Kind regards,
>Alex Granovsky
>On Wed Jan 24 '18 11:37pm, David Shobe wrote
>>How can I improve on GUESS=HUCKEL when it fails to perform?

>>At least I'm assuming the initial guess is at fault and not the choice of parameters EXTRAP DAMP SHIFT DIIS and SOSCF. This is because from beginning to end of the DFT orbital calculation, I am getting wildly different energies from one iteration to the next.

>>I tried SnI3+ (which is a closed shell), but got the same result. So my question is: now what?

>>I could try to swap occupied and unoccupied orbitals with NORDER, but I'm flying blind.

>>If you're wondering: Yes, I do have diffuse functions. SnI3 converges fine when you omit them.  But I think I need the diffuse functions for accuracy.

>>Regards, and thanks for any help,
>>--David Shobe

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