From chemistry-request: at :www.ccl.net Fri Feb 26 12:49:28 1999 Received: from mailhost.lanl.gov (mailhost.lanl.gov [128.165.3.12]) by www.ccl.net (8.8.3/8.8.6/OSC/CCL 1.0) with ESMTP id MAA19077 Fri, 26 Feb 1999 12:49:27 -0500 (EST) Received: from [128.165.22.209] (machgs.lanl.gov [128.165.22.209]) by mailhost.lanl.gov (8.9.3/8.9.3/(cic-5, 2/8/99)) with SMTP id KAA11810 for ; Fri, 26 Feb 1999 10:49:27 -0700 X-Sender: schrecke -8 at 8- t12mail.lanl.gov Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 26 Feb 1999 10:53:00 -0600 To: CHEMISTRY;at;www.ccl.net (CCL) From: schrecke $#at#$ t12.lanl.gov (Georg Schreckenbach) Subject: summary: MO & state symmetry in G94/98 Dear CCL, this is my summary regarding my question posted last week. I tried to make GAUSSIAN determine the symmetry of the MOs in a DFT calculation. The result, in short: it is not possible, at least not for my molecule ([UO2Cl4]2-, D4h, with an ECP basis set on U.) I got a number of interesting suggestions, and I tried them all but nothing helped. This seems to be an artefact of GAUSSIAN, and other programs don't have the problem (e.g. ADF or Jaguar, cf. also answer #5 below.) Here is what I did try (without success, as I said already) - "Symm=Loose" - "Conver=11", together with IntRep - various finer integration grids - fine integration grids combined with "SCF=(Conver=11, Intrep) - "QC" combined with all of the above Thanx to all who replied, and best regards, Georg ----------------------------------- The detailed answers: #1: Original question: Dear all, while running a DFT single point on a symmetric (D4h) molecule using Gaussian98, I get the message that the program is unable to determine the symmetry of some orbitals, and consequently of the electronic state. This is problematic since I try to calculate excited states, and if the MO symmetries are unknown, then so are the excited state symmetries. Is there a reason for this behavior? Is there a way to make the program find the appropriate symmetry labels for the orbitals? -- I tried already SCF=(IntRep,Tight) but it had no effect. Thank you very much! -- I'll summarize if there is any interest. Best regards, Georg ----------------------------------- #2 From: theis /at\kalium.kiku.dk Date: Mon, 22 Feb 1999 09:09:42 +0100 Dear Dr. Schreckenbach, I would be very intersted in a summary. I once asked Doug Fox almost the same question, but I never got a reply that enabled me to work my way around the problem. I have a feeling that only thing one can to do is to determine the symmetry of the state manually. All the best, Theis Soelling, ** ** ** ** Mr. Theis Ivan Solling ** ** ** ** ** Department of Chemistry ****** ****** University of Copenhagen ** ** ** DK-2100 Copenhagen ** ** ** Ph. 45-3532-0187/Fax. 45-3532-0212 ----------------------------------- #3 Date: Fri, 19 Feb 1999 17:07:57 -0600 From: John McKelvey Is there a symmetry threshold value available? i.e. Symmetry is determined by comparing ao coefficients. The "same" or "not the same" is measured by how large the difference between the coefficients is... Just looked in the manual... try SYMMETRY=LOOSE .... You might say this is a workaround, but the differences judged ma be of the order of 10**-5 or smaller.. is this important? John McKelvey NCSA ----------------------------------- #4 From: hofmann "-at-" thkin.pci.uni-leipzig.de Date: Mon, 22 Feb 1999 16:20:35 +0000 (CUT) Hello Georg, we've had a similar problem. It was solved by doing a very tight SCF-Calculation. We used scf=(conver=11,intrep) and the unresolved orbitals become nice. Good luck Alex ------------------------------------------------------------------------- | | | | Alexander Hofmann | Phone (office) +49-341-97-36337 | | Wilhelm-Ostwald-Institut fuer | Fax (office) +49-341-97-30099 | | Physikalische und Theoretische | | | Chemie | | | Augustusplatz 10-11 | hofmann*- at -*thkin.pci.uni-leipzig.de | | | | | D-04109 Leipzig | http://www.uni-leipzig.de/~quant | | | /hofmann/alex.html | ------------------------------------------------------------------------- ----------------------------------- #5 From: George Vacek Date: Wed, 24 Feb 1999 13:39:05 -0800 (PST) Georg, %% using Gaussian98, I get the message that the program is unable to %% determine the symmetry of some orbitals, and consequently of the %% electronic state. I'm not sure why Gaussian has this problem. It has been around since the early days of Gaussian (certainly 92, most probably earlier). Maybe it is an artifact of the fact that the early versions of Gaussian didn't use symmetry at all. In principal orbital symmetry identification is something that is easy to do right. We've gotten compliments on our Jaguar program because it does properly identify orbital symmetry and everyone is used to the crappy behaviour of Gaussian. Regards, George =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= George Vacek + Schrodinger, Inc. (503) 299-1150 + 121 SW Morrison, Suite 1212 vacek -A_T- schrodinger.com + Portland, OR 97204 http://www.schrodinger.com/~vacek/ The phrase "rule of thumb" is derived from an old English law which stated that you couldn't beat your wife with anything wider than your thumb. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=