From owner-chemistry@ccl.net Thu Mar 12 11:02:01 2009 From: "Roman D Gorbunov rgorbuno{}aecom.yu.edu" To: CCL Subject: CCL:G: Error imposing constraints in Gaussian Message-Id: <-38821-090312103720-2183-eDAy5arUVRUdMo0s1jdFiw ~ server.ccl.net> X-Original-From: "Roman D Gorbunov" Date: Thu, 12 Mar 2009 10:37:15 -0400 Sent to CCL by: "Roman D Gorbunov" [rgorbuno-,-aecom.yu.edu] Dear CCL Subscribers, I try to run a geometry optimization in which the structure of the molecule is restricted to be planar (this is a 2 nucleotide system, a base-pare). My calculation crashed. In the end I have the following message: Iteration100 RMS(Cart)= 0.00004173 RMS(Int)= 0.00140344 New curvilinear step not converged. Error imposing constraints Error termination via Lnk1e in /opt/g03/l103.exe at Mon Mar 9 13:29:22 2009. Job cpu time: 0 days 6 hours 9 minutes 54.8 seconds. File lengths (MBytes): RWF= 134 Int= 0 D2E= 0 Chk= 20 Scr= 1 I found that in the CCL list peoples already discussed this problem: http://server.ccl.net/cgi-bin/ccl/message-new?2003+05+23+007. However, this message does not help me. It is written there that the problem can appear if "the fixed torsional or dihedral angles are far from that of the starting geometry". It is not my case since I do NOT have 2 values for the same coordinate("starting" one and "fixed" one). For every internal coordinate I have only one value and than in the end of the input file I specify the internal coordinates which have to be fixed. In the cited message also written that problem can appear if "you fix too many redundant coordinates at once causing Gaussian to have a difficult time funneling the forces in the remaining coordinates". It seams to be my case. I fix a lot of dihedral angles to force the structure to be planar. So, i probably know what is the reason of the problem but I still do not know how to solve the problem. Can anybody help me with that? Thank you in advance, Roman.