From owner-chemistry@ccl.net Mon Nov 3 11:57:01 2014 From: "Close, David M. CLOSED^mail.etsu.edu" To: CCL Subject: CCL:G: Tweaking Gaussian to remove imaginay frequency Message-Id: <-50692-141103104857-15050-nDdxlT4yoLO+/uSz8p7RKg]![server.ccl.net> X-Original-From: "Close, David M." Content-Language: en-US Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="us-ascii" Date: Mon, 3 Nov 2014 15:48:50 +0000 MIME-Version: 1.0 Sent to CCL by: "Close, David M." [CLOSED%x%mail.etsu.edu] John: "Tweaks Under Gaussian?" No. What you have to do is animate the frequency output to look at the particular vibration that involves this negative frequency. Then you have to make small changes in the coordinates of this motion in attempts to get off the optimization off this local minima in hopes of going towards the global minima. There are free programs on the internet to do this, and I can send one to you. But with a little practice you can guess at which numbers to alter. Regards, Dave Close. -----Original Message----- > From: owner-chemistry+closed==etsu.edu]_[ccl.net [mailto:owner-chemistry+closed==etsu.edu]_[ccl.net] On Behalf Of John Simmie john.simmie===nuigalway.ie Sent: Monday, November 03, 2014 8:46 AM To: Close, David M. Subject: CCL:G: Tweaking Gaussian to remove imaginay frequency Sent to CCL by: "John Simmie" [john.simmie%%nuigalway.ie] In running a B3LYP/6-311G(2d,d,p) geometry/frequency calculation of the all-trans conformer of succinic acid 0,1 1 -2.350831000 2.938540000 0.000000000 8 -1.422415000 2.661642000 0.000000000 8 -2.436452000 0.657377000 0.000000000 6 -1.422415000 1.308099000 0.000000000 6 -0.015143000 0.761522000 0.000000000 1 0.511721000 1.167432000 0.867888000 1 0.511721000 1.167432000 -0.867888000 6 0.015143000 -0.761522000 0.000000000 1 -0.511721000 -1.167432000 -0.867888000 1 -0.511721000 -1.167432000 0.867888000 6 1.422415000 -1.308099000 0.000000000 8 2.436452000 -0.657377000 0.000000000 8 1.422415000 -2.661642000 0.000000000 1 2.350831000 -2.938540000 0.000000000 I end up with a imaginary frequency. Given THAT functional and basis set are there any general tweaks under Gaussian-09 that I can make which will eliminate it? Should one loosen or tighten limts or what? Opt-VTight does not help ... john.simmie at NUIGalway.iehttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt