From chemistry-request _-at-_)ccl.net Tue Nov 25 12:38:08 2003 Received: from gothmog.gpcc.itd.umich.edu (gothmog.gpcc.itd.umich.edu [141.211.2.180]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id hAPHbbNL008948 for ; Tue, 25 Nov 2003 12:37:37 -0500 Received: from rygar.gpcc.itd.umich.edu (rygar.gpcc.itd.umich.edu [141.211.2.202]) by gothmog.gpcc.itd.umich.edu (8.9.3p2/4.3-mailhub) with ESMTP id MAA07728 for ; Tue, 25 Nov 2003 12:37:36 -0500 (EST) Received: from localhost (jyudenfr:~at~:localhost) by rygar.gpcc.itd.umich.edu (8.9.3p2/5.1-client) with ESMTP id MAA02212 for ; Tue, 25 Nov 2003 12:37:36 -0500 (EST) Precedence: first-class Date: Tue, 25 Nov 2003 12:37:36 -0500 (EST) From: Joslyn Y Kravitz X-X-Sender: jyudenfr:at:rygar.gpcc.itd.umich.edu To: CHEMISTRY:at:ccl.net Subject: Re: CCL:D orbitals in Gaussian In-Reply-To: <000c01c3b06d$db989680$0901a8c0 # - at - # mmserver> Message-ID: References: <001101c3b061$881f8830$80e12844[ AT ]Garfield> <000c01c3b06d$db989680$0901a8c0[ AT ]mmserver> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Status: No, hits=-1.0 required=7.0 tests=IN_REP_TO,REFERENCES,USER_AGENT_PINE version=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) I have received some helpful responses to my question about orienting orbitals in Gaussian. The main suggestions had to do with symmetry, but since my molecules are C1, that doesn't come into play. What does come into play is the "NoSymmetry" keyword. This is not the same as "GUESS=NoSymm" which has to do with the symmetry of the initial guess. This "NoSymmetry" command tells Gaussian, "I don't care what you think the major symmetry element is, I want my molecule to stay just the way I entered it!" Or more formally, it prevents gaussian from putting the coordinates into the standard orientation, so it uses the input coordinates all the way through. Thanks all, Joslyn Kravitz >===== Original Message From Joslyn Kravitz ===== >Hello, > >For some time I have been trying to use Gaussian to calculate the >molecular orbitals for some vanadyl compounds. I want to see which atomic >orbitals from the V are contributing to the homo, somo and lumo. I have >obtained lovely pictures of the MO's but I want to be able to quantify >the atomic orbital contributions. According to an e-mail I received from >the help line at Gaussian the orbitals are numbered like this: > >d0 = z^2 (really 3z^2-r^2) >d+1 = xz >d-1 = yz >d+2 = x^2 - y^2 >d-2 = xy > >Unfortunately, since Gaussian puts the molecules into the standard >orientation the atomic orbital names in the output no longer correspond >to the ones you normally think of based on symmetry. That is, you would >expect the dz^2 to be oriented along the V=O bond and all the others to >fall in place around it, but that doesn't seem to be true. The dz^2 >orbital is oriented along whatever random direction is designated the z >axis in the "standard orientation" and then the other orbitals fall in >around that. Unfortunately, that makes interpreting the results a little >difficult, especially when different compounds are oriented differently, >so that the atomic orbitals are not named consistently between compounds. > >I have tried using input coordinates that place the V=O bond along a >z-axis and setup the equatorial plane in an appropriate way and then >running a "NoSymm" calc, but that doesn't seem to help at all. Does >anyone know how I can convert my calculated orbitals to more "chemically >intuitive" ones, or at the very least, force Gaussian to not reorient the >molecule? > >Thank you, >Joslyn Kravitz >Depart. Of Chem. >University of Michigan