RE: G94 and G98
Dear Emad,
G94 and G98 DFT differ in at least two points.
1) The default weighing scheme for the numerical integration is now
Stratmann/Scuseria. It was different in G94 (the Becke scheme ?).
2) The SCF cycles are now started with a superposition of states instead of the
pure guess. This _might_ lead to differences, but does not seem to be the case
in your calcs.
Stefan
______________________________________________________________________
Dr. Stefan Fau
Fachbereich Chemie, AK Frenking
Philipps-Universität Marburg
35032 Marburg, Germany
fau |-at-| chemie.uni-marburg.de
> -----Original Message-----
> From: Computational Chemistry List [mailto:chemistry-request |-at-| ccl.net]On
> Behalf Of Emadeddin Tajkhorshid
> Sent: Friday, April 16, 1999 6:03 AM
> To: ccl CCL
> Subject: CCL:G94 and G98
>
>
> Dear CCL
>
> I have experienced something using geometry optimization in G94 and G98
> that I would like to check with you. I started from a G94-optimized set
> of coordinates for glycine. Using a DFT method (B3LYP/6-31G**), on the
> same platform (IBM/SP2) I started the same job in G94 and G98. These two
> jobs, while having the same optimization criteria (Default values) and
> the same starting geometries (and I suppose the same initial guess?)
> give different results. In one case the geometry is optimized and in the
> other case, the job does not meet the 'Maximum displacement' and 'RMS
> displacement' criteria after the first cycle. Examination of the energy
> also shows that we have different values after the first SCF.
>
> Although the differences in this case are not very large, I would like
> to know why they happen. If I am not mistaken there are some
> modifications with respect to the optimizer in G98, but I think in the
> case of this example, the difference is happening at the level of
> wavefunction.
>
> Did anybody else experience such differences at the wavefunction or
> geometry level? If so, how large are they?
>
>
> **********************G94 job*************************************
> First SCF:
>
> SCF Done: E(RB+HF-LYP) = -284.437033067 A.U. after 15 cycles
> Convg = .4529D-08 -V/T = 2.0089
> S**2 = .0000
> KE= 2.819396660737D+02 PE=-1.026794554909D+03 EE= 2.802029338205D+02
>
> :::::
> Item Value Threshold Converged?
> Maximum Force .000028 .000450 YES
> RMS Force .000009 .000300 YES
> Maximum Displacement .000293 .001800 YES
> RMS Displacement .000108 .001200 YES
> Predicted change in Energy=-1.479922D-08
> ******************************************************************
>
> **********************G98 job*************************************
> First SCF:
>
> SCF Done: E(RB+HF-LYP) = -284.437035418 A.U. after 15 cycles
> Convg = .4595D-08 -V/T = 2.0089
> S**2 = .0000
> KE= 2.819396670445D+02 PE=-1.026794557138D+03 EE= 2.802029327275D+02
>
> ::::
> Maximum Force .000028 .000450 YES
> RMS Force .000012 .000300 YES
> Maximum Displacement .004390 .001800 NO
> RMS Displacement .001377 .001200 NO
> Predicted change in Energy=-7.549560D-08
> ******************************************************************
>
> --
> Emad
> *********************************************************************
> E. Tajkhorshid, Ph.D.
> German Cancer Research Center; DKFZ Tel: +49 6221 42 2340
> Dept. Molecular Biophysics (H0200) FAX: +49 6221 42 2333
> P.O.Box 101949 http://genome.dkfz-heidelberg.de/users/emad
> 69009 Heidelberg, Germany Email: E.Tajkhorshid |-at-|
DKFZ-Heidelberg.de
> *********************************************************************
> * "Science is talking to each other"
*
> *********************************************************************
> -= This is automatically added to each message by mailing script =-
> CHEMISTRY |-at-| ccl.net -- To Everybody |
> CHEMISTRY-REQUEST |-at-| ccl.net -- To Admins
> MAILSERV |-at-| ccl.net -- HELP CHEMISTRY or HELP SEARCH
> CHEMISTRY-SEARCH |-at-| ccl.net -- archive search | Gopher:
> gopher.ccl.net 70
> Ftp: ftp.ccl.net | WWW: http://www.ccl.net/chemistry/ | Jan:
> jkl |-at-| ccl.net
>
>