From owner-chemistry $#at#$ ccl.net Thu Apr 16 09:14:00 2009 From: "Alexander Hoepker achoepker]*[gmail.com" To: CCL Subject: CCL:G: geometry optimization convergence problem Message-Id: <-39089-090416090912-27953-vcTZEDKhWLqd55fr9YW1UQ||server.ccl.net> X-Original-From: Alexander Hoepker Content-Type: multipart/alternative; boundary=000e0cd402ac1234bc0467abc4c2 Date: Thu, 16 Apr 2009 09:08:53 -0400 MIME-Version: 1.0 Sent to CCL by: Alexander Hoepker [achoepker^^^gmail.com] --000e0cd402ac1234bc0467abc4c2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Dear CCL community, I am having difficulty with a particular geometry optimization using B3LYPlevel of theory using a 6-31G(d) basis set while constraining a bondlength using the ModRedundantkeyword in Gaussian. The geometry sequence energies drop nicely but then plateau at an average value while oscillating endlessly without ever converging. The Maximum and RMS Forces have converged whereas the Displacements have not. Would GDIIS help with this? Any suggestions would be very much appreciated. Thanks, Alexander Hoepker Cornell University Department of Chemistry and Chemical Biology --000e0cd402ac1234bc0467abc4c2 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Dear CCL community,

I am having difficulty with a particular g= eometry optimization using B3LYP level of theory using a 6-31G(d) basis set while con= straining a bondlength using the ModRedundant keyword in Gaussian. The geometry = sequence energies drop nicely but then plateau at an average value while os= cillating endlessly without ever converging. The Maximum and RMS Forces hav= e converged whereas the Displacements have not. Would GDIIS help with this?
Any suggestions would be very much appreciated.

Thanks,

Alexander Hoepker
Cornell Uni= versity
Department of Chemistry and Chemical Biology
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