From chemistry-request@ccl.net Wed May 28 11:36:50 2003 Received: from kelly.bath.ac.uk (kelly.bath.ac.uk [138.38.32.20]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SFangC008053 for ; Wed, 28 May 2003 11:36:50 -0400 Received: from midge.bath.ac.uk ([138.38.32.34] ident=mmdf) by kelly.bath.ac.uk with smtp id 19L2yu-0006nm-6R; Wed, 28 May 2003 16:36:48 +0100 Received: from prpcn144 ( prpc-n144.bath.ac.uk [138.38.128.144] ) by bath.ac.uk id aa16287 ; 28 May 2003 16:36 +0100 From: James Robinson To: "Daniel R. Rohr" , ccl Subject: RE: Eigenvalues of hessian Date: Wed, 28 May 2003 16:37:04 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Importance: Normal In-Reply-To: <1054131647.16827.13.camel@charly> X-Scanner: *19L2yu-0006nm-6R*hmabWlK1Neg* Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by server.ccl.net id h4SFaogC008056 Some numerical methods use small perturbations in the x, y and z planes to compute force constants. Unfortunately this effectively contaminates the calculation with net translations. Could this be happening in your Hessian calc? James (if I wrong, do let me know!) -----Original Message----- From: Computational Chemistry List [mailto:chemistry-request.-at-.ccl.net]On Behalf Of Daniel R. Rohr Sent: 28 May 2003 15:21 To: ccl Subject: CCL:Eigenvalues of hessian Hi CCLers Does anybody of you know, why there are more than 3N-6 nonzero eigenvalues of the hessian? I am especially interested in the question, whether this error is due to the errors made by differentiation or whether they are due to an error within the method itself. I usually get only 3 zero eigenvalues. No matter if the hessian is calculated on a stationary point or not. Thanks for your help Daniel Rohr -- ----------------------------------------------------------------------- Daniel Rohr Fachbereich Chemie der Philipps-Universitdt Tel.: +49-6421-28-25686 Hans-Meerwein-Stra_e Fax.: +49-6421-28-25566 D-35043 Marburg eMail: rohrd.-at-.stud-mailer.uni-marburg.de Germany ----------------------------------------------------------------------- -= This is automatically added to each message by mailing script =- To send e-mail to subscribers of CCL put the string CCL: on your Subject: line and send your message to: CHEMISTRY.-at-.ccl.net Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST.-at-.ccl.net HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs If your mail is bouncing from CCL.NET domain send it to the maintainer: Jan Labanowski, jkl.-at-.ccl.net (read about it on CCL Home Page) -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+