From takanori.kanazawa.,at,.pharma.novartis.com Fri Mar 13 06:17:34 1998 Received: from gatekeeper.chbs.ciba.com for takanori.kanazawa _-at-_)pharma.novartis.com by www.ccl.net (8.8.3/950822.1) id FAA29035; Fri, 13 Mar 1998 05:59:40 -0500 (EST) From: Received: from mailhub by gatekeeper.chbs.ciba.com; (5.65v3.2/1.1.8.2/12Mar96-0208PM) id AA05620; Fri, 13 Mar 1998 11:59:09 +0100 Received: from nts1.novartis.com ([192.168.50.131]) by mta3.is.chbs (8.8.5/8.8.5) with SMTP id LAA07653 for ; Fri, 13 Mar 1998 11:59:33 +0100 (MET) Received: by nts1.novartis.com(Lotus SMTP MTA SMTP MTA v1.1.04 (495.1 10-24-1997)) id 412565C6.003C573F ; Fri, 13 Mar 1998 11:59:04 +0100 X-Lotus-Fromdomain: PH #at# N1 To: chemistry#* at *#www.ccl.net Message-Id: <492565C6.003A3A0F.00- at -nts1.novartis.com> Date: Fri, 13 Mar 1998 19:58:41 +0900 Subject: G94 geometry optimization with constraints Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Dear CCLers, This is the second time I post here a question. Last time I posted here a question about G94 check point file, I got a lot of answers and I'm grateful to all who gave me replies. This time I have a question about geometry optimization of a dimeric molecule. Each monomer unit is an almost planar molecule except one methyl group. I did geometry optimization of the dimer by fixing the dimer molecule on a plane (dihedral angles between the monomer units is fixed to 0 or 180). In the course of the geometry optimization, intermolecular geometry begins to deviate from planarity and finally the optimization job stops with the following error messages --------------------------------------------------------------------------- ------- Convergence failuer -- run terminated. Error termination via Link1e in /home/Gaussian/g94/l502.exe. Job cpu time: .... ............ --------------------------------------------------------------------------- ------- Before this termination, messages like the following are repeated ------------------------------------------------------------------ Energy Rises -- skip Quadratic search. Quartic linear search produced a step of -0.99578. ....... ....... Iteration 10 RMS(Cart)=************ RMS(Int)=************ Iteration 11 RMS(Cart)=************ RMS(Int)=************ ......... ------------------------------------------------------------------ I guess the reason for this job failuer is that the dihedral angle between monomer units changed abruptly from 0 to 180 or 180 to 0, and the geometry optimization became uncontrollable. Is this right? Is there any way to overcome this problem? I used the default redundant internal coordinate optimization and the keyword "Opt"(not Fopt) I'd appreciate any suggestons very much. With best regards, Takanori ********************************************** Takanori Kanazawa e-mail : takanori.kanazawa#* at *#pharma.novartis.com Drug Discovery Group / CAMM Novartis Pharma Japan **********************************************