PC GAMESS/Firefly-related discussion club

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Richard
bonarlaw@liv.ac.uk

Older basis sets such as 6-31G(d) (and I think D95(d)) were developed/defined to use cartesians, so may need to be run D6 to reproduce literature data. However for large molecules its more efficient to run these D5 as well - I haven't noticed any chemically significant D6/D5 differences, at least for the sort of molecules we work on.

Richard

On Wed Jun 10 '09 10:36am, Stefan Boresch wrote
-----------------------------------------------
>Richard,

>On Tue Jun 9 '09 11:40pm, Richard wrote
>---------------------------------------
>>To get the same answer specify spherical harmonic basis functions by adding ISPHER=1 (gamess-us) or D5=.t. (firefly) in the $CONTRL group.

>thank you, that's it!

>>6-31G has no d (and higher) functions so this cartesian/harmonic confusion doesn't arise.

>Let me just follow up with an ignorant question: If I am not interested in reproducing, e.g., a Turbomole run, is it an error
>not to specify ISPHER=1 (gamess-us) or D5=.t. in combination with
>aug-cc-pVTZ, or is this a "matter of taste"?

>Best regards,

>Stefan

>>On Tue Jun 9 '09 6:01pm, Stefan Boresch wrote
>>---------------------------------------------
>>>I am making first steps in quantum chemistry using Gamess-US, Firefly and psi3. When I do a single point calculation of, e.g., water using
>>>e.g. a 6-31G basis set ($BASIS  GBASIS=N31 NGAUSS=6 $END), I get identical energies with all three programs mentioned.  However, when going to larger basis sets (e.g., aug-cc-pVTZ) the Gamess-US/Firefly
>>>gives a noticeable different result from psi3. A collegue verified for me that the psi3 result can be reproduced using Turbomole and Columbus.

>>>This is the input file I use for Gamess-US (downloaded about mid-may):

>>> $CONTRL SCFTYP=RHF RUNTYP=ENERGY COORD=UNIQUE $END
>>> $BASIS  GBASIS=ACCT $END
>>> $DATA
>>>basis set comparison
>>>C1
>>>Oxygen       8.0     0.0         0.0     0.0
>>>Hydrogen     1.0    -0.758       0.0     0.545
>>>Hydrogen     1.0     0.758       0.0     0.545
>>> $END

>>>For firefly, I specify the basis set information in the $DATA
>>>block (basis set data downloaded from EMSL  Basis Set Exchange Library)

>>>And here are the energies:

>>>Columbus:  -76.0609783763 Hartree
>>>Turbomole: -76.06097837464 Hartree
>>>psi3:      -76.060978374163 Hartree

>>>Gamess-US: -76.0615148616 Hartree
>>>Firefly:   -76.0615148610 Hartree

>>>Needless to say, I am confused -- maybe someone can enlighten me.
>>>Thanks in advance,

>>>Stefan Boresch
>>>
>>>
>>>
>>>