From chemistry-request _-at-_)server.ccl.net Thu Jul 19 11:26:18 2001 Received: from garnet.INS.cwru.edu (root # - at - # [129.22.8.233]) by server.ccl.net (8.11.0/8.11.0) with ESMTP id f6JFQI531784 for ; Thu, 19 Jul 2001 11:26:18 -0400 Received: from gavin (chem51286.CHEM.CWRU.Edu [129.22.129.217]) by garnet.INS.cwru.edu with SMTP (8.11.2+cwru/CWRU-3.8) id f6JFQIY06492; Thu, 19 Jul 2001 11:26:18 -0400 (EDT) (from hxt10 _-at-_)po.cwru.edu for ) Message-ID: <001201c11067$d550c200$d9811681 ":at:" cwru.edu> Reply-To: "Hui-Hsu $Gavin$ Tsai" From: "Hui-Hsu $Gavin$ Tsai" To: Subject: negative vibration frequency Date: Thu, 19 Jul 2001 11:31:08 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01C11046.4DFBFE80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01C11046.4DFBFE80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi CCLers: I have a question about the negative frequency in the frequency = calculation. For larger or complicate molecule, the geometry optimization usually can = not reach the minimum point, but the saddle point with some negative and = small vibration frequencies. To adapt and try to reoptimize the molecule = wastes CPU. Is there any geometry optimization algorithm which can follow the = negative frequency and reach the minimum point automatically? any comment is welcome! Thanks! Gavin=20 ------=_NextPart_000_000F_01C11046.4DFBFE80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi CCLers:

I have a question = about the=20 negative frequency in the frequency calculation.

For larger or complicate molecule,=20 the geometry optimization usually can not reach the minimum = point,=20 but the saddle point with some negative and small vibration=20 frequencies. To adapt and try to reoptimize the molecule wastes=20 CPU.

Is there any geometry optimization = algorithm which=20 can follow the negative frequency and reach the minimum point=20 automatically?

any comment is welcome! = Thanks!

Gavin

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