CCL:G: Different single-point DFT energy between GAMESS and Gaussian

- Christopher Cramer suggested that different spatial orientation may cause different results. The "nosymm" Gaussian keyword indeed suppreses any orientation changes, so input orientation is used throughout the calculations. GAMESS doesn't change the orientation by default, so calculations performed using "nosymm" are made on the same geometry. I was curious if changing the initial orientation (called "InitOr in the table below - different than the orientation above) to the standard one, can change the results significantly. If "nosymm" is not present, Gaussian rotates the molecule to the standard orientation (StdOr). In order to do the same using GAMESS, "COORD=PRINAXIS" keyword is required. I've found out that when using standard orientation from the Gaussian output and pasting it to the GAMESS input (now without "coord=prinaxis), GAMESS gives different result than by rotating the molecule to the principal axis by itself! Therefore in all subsequent GAMESS calculations I was using standard orientation from Gaussian output (the one above). The results are presented below (using M05/cc-pVDZ and grid(75,302)), together with HF energies, which are pretty much reproducible, and M05 calculations using much better than standard grid (250,974):

On Tue, May 25, 2010 at 7:53 PM, Piotr Nowak piotrnowak[*]student.uw.edu.pl <owner-chemistry:+:ccl.net> wrote:

First of all, thanks everyone for response. Some questions and suggestions appeared; I'll try to answer them briefly:

-I've been using exactly the same structures for the single point energy calculations;

-I have been using spherical harmonics in both programs. Gaussian uses them by default, and I have ensured their use in GAMESS with "ISPHER=+1" keyword. The number of cartesian basis fuinctions is the same;

-Gaussian manual states that default grid uses 75 radial shells and 302 angular points/shell. I have been using the same grid in GAMESS thanks to "NRAD=75" and "NLEB=302" keywords. I also suspected that grid handling might be implemented differently in both programs, therefore I tried some "super-ultra-extra-fine" grid with 250 radial shells and 974 angular points/shell (using "Int(Grid=250974)" keyword in Gaussian). Unluckily, the energy difference remained within the same order of magnitude as it was with former grid;

-The relative energies are still different. If you compare e.g. different geometries of the same molecule, or activation energies, the error is still 10^(-4) hartree.

I would agree with Soren - there must be some "hidden" adjustable parameters, but I have no idea which one can cause these differences. I still hope it is possible to get the same results using both programs.

Kind regards,
Piotr

On Tue, May 25, 2010 at 12:50 AM, Piotr Nowak piotrnowak!^!http://student.uw.edu.pl" target="_blank">student.uw.edu.pl <owner-chemistry]^[ccl.net> wrote:

Sent to CCL by: "Piotr Nowak" [piotrnowak~!~student.uw.edu.pl]
Dear CCL users,

I'm trying to reproduce single point energy obtained with Gaussian 03 using
GAMESS US. Hartree-Fock energy is almost exactly the same e.g.
Gaussian: -1849.26414782
GAMESS: -1849.2641478646

Unfortunately my attempts to get the same results using DFT failed. The
energy differences between both programs are unreasonably huge. Here are some
examples of results for different functionals (the same case as above-
mentioned HF example):
M05-2X
Gaussian: -1855.79754118
GAMESS: -1855.7976587495
SVWN5
Gaussian: -1845.45112047
GAMESS: -1845.4510666810
Slater (also known as Dirac, one of the simplest LDA functionals, so I'm sure
it has the same definition in both programs)
Gaussian: -1833.20351470
GAMESS: -1833.2034704727

I have done those calculations using the same grid, using tight convergence
criteria. I've found out that Gaussian uses slightly different cc-pVDZ basis
set than the one present in Basis Set Exchange, but using this basis set with
GAMESS has left the results unchanged. I have also tried different guesses,
and SCF algorithms, but without success.

Here are keywords used in inputs for above calculations.
Gaussian:
#p m05/cc-pvdz nosymm iop(6/7=3) scf=tight

GAMESS:
$BASIS EXTFIL=.TRUE. GBASIS=CCPVDZGN $END
$CONTRL ISPHER=+1 SCFTYP=RHF RUNTYP=ENERGY DFTTYP=M05 $END
$SYSTEM PARALL=.TRUE. MWORDS=200 $END
$SCF DIRSCF=.TRUE. DIIS=.TRUE. $END
$DFT NRAD=75 NLEB=302 $END

I would appreciate any kind of help.
Best regards,
Piotr Nowak

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