From chemistry-request@ccl.net Thu Jun 17 14:53:06 2004 Received: from mercury.ccmr.cornell.edu (mercury.ccmr.cornell.edu [128.84.231.97]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id i5HJr50v004081 for ; Thu, 17 Jun 2004 14:53:05 -0500 Received: from bashful.ccmr.cornell.edu (bashful.ccmr.cornell.edu [128.84.241.122]) by mercury.ccmr.cornell.edu (8.12.10/8.12.10) with ESMTP id i5HJvWAV017261 for ; Thu, 17 Jun 2004 15:57:34 -0400 Received: from localhost (cc236@localhost) by bashful.ccmr.cornell.edu (8.12.10/8.12.10) with ESMTP id i5HJvWLa023163 for ; Thu, 17 Jun 2004 15:57:32 -0400 Date: Thu, 17 Jun 2004 15:57:32 -0400 (EDT) From: Connie Chang To: chemistry)at(ccl.net Subject: Re: CCL:Help with Gaussian error message Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Virus-Scanned: clamd / ClamAV version 0.70, clamav-milter version 0.70j X-Spam-Status: No, hits=2.5 required=7.5 tests=FROM_ENDS_IN_NUMS, IMPRONONCABLE_1 autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net Hi CCLers Thanks to all those who replied to my question about the Gaussian error I received: No NMR shielding tensors so no spin-rotation constants. | Leave Link 601 at Fri Jun 11 14:36:46 2004, MaxMem= 6291456 cpu: 1.0 | (Enter C:\g03w\l9999.exe) I put in the Nosymm keyword and that seems to have fixed the problem. Benzene as many of you replied tends to want to be symmetric, but when a charge is placed on it, that symmetry is disrupted and Gaussian needs to know that. Pablo Vitoria's reply: Yes, that's it, the error comes from the fact that Gaussian couldn't complete the optimization. You can try increasing the maximum number of optimization steps to N with opt=(maxcycle=N). Pedro's reply: Are you trying negative charge? Benzene is not stable with negative charge and could affect your convergence (it is not a rule though). Try B3PW91, I usually work with that one and was able to have benzene with charge -1 converge (although giving a larger energy than the neutral). I have never tried charge +1, however it is not difficult to imagine that you will also get higher energy than for the neutral And Jarek Panek's reply: Yes, I guess you have it right - Gaussian exceeded maximum number of steps (probably earlier you saw message like this below): ! Non-Optimized Geometry ! The reason is, as far as my intuition goes, that benzene is highly symmetric. Now you want to compute the cation, and the cation is probably not exactly "aromatic" any more! I think the bond lengths will be no more equal... If they are (see the Non-Optimized geometry in the file), restart the job with artificially displaced one of the carbon atoms) Thanks again! Connie From chemistry-request@ccl.net Thu Jun 17 14:55:16 2004 Received: from mercury.ccmr.cornell.edu (mercury.ccmr.cornell.edu [128.84.231.97]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id i5HJtG0v004189 for ; Thu, 17 Jun 2004 14:55:16 -0500 Received: from bashful.ccmr.cornell.edu (bashful.ccmr.cornell.edu [128.84.241.122]) by mercury.ccmr.cornell.edu (8.12.10/8.12.10) with ESMTP id i5HJxjAV017570 for ; Thu, 17 Jun 2004 15:59:45 -0400 Received: from localhost (cc236@localhost) by bashful.ccmr.cornell.edu (8.12.10/8.12.10) with ESMTP id i5HJxjOt023233 for ; Thu, 17 Jun 2004 15:59:45 -0400 Date: Thu, 17 Jun 2004 15:59:45 -0400 (EDT) From: Connie Chang To: chemistry(at)ccl.net Subject: CCL: Another Gaussian question about spin Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Virus-Scanned: clamd / ClamAV version 0.70, clamav-milter version 0.70j X-Spam-Status: No, hits=1.5 required=7.5 tests=FROM_ENDS_IN_NUMS autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net Hi -- I was wondering if 1) Gaussian can calculate the exchange energy and 2) if there's a way to specify which spin electron you want to add? Also, 3) is there a way to apply a magnetic field to a molecule? As far as I know, if you want to add a charge onto a molecule, you just write before the molecule specification: -1 2 where the -1 is the charge and the 2 is the multiplicity. Thanks in advance... Connie