From owner-chemistry@ccl.net Tue Jun 26 05:36:01 2007 From: "Igor Avilov avilovi,+,averell.umh.ac.be" To: CCL Subject: CCL:G: G03 optimization convergence limits Message-Id: <-34567-070626045922-7814-K6On1L9veuAbMNKbMh3bNw[A]server.ccl.net> X-Original-From: "Igor Avilov" Content-class: urn:content-classes:message Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C7B7CB.AA8FD0CB" Date: Tue, 26 Jun 2007 10:26:15 +0200 MIME-Version: 1.0 Sent to CCL by: "Igor Avilov" [avilovi[#]averell.umh.ac.be] This is a multi-part message in MIME format. ------_=_NextPart_001_01C7B7CB.AA8FD0CB Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Dear John, =20 Try using Opt(GDIIS), it helps in cases where the potential energy surface is very flat.=20 =20 Best wishes, Igor Avilov. ________________________________ > From: owner-chemistry#ccl.net [mailto:owner-chemistry#ccl.net]=20 Sent: lundi 25 juin 2007 19:35 To: Igor Avilov Subject: CCL: G03 optimization convergence limits Greetings, Often when there are freely rotating methyl groups one can find that the energy and gradients have converged but there is a large displacement because of the freely rotating or librating methyl group, and a lot of cpu time can go into getting the methyl group to settle down. Does anyone know how to set IOP info to allow a way around this problem [where convergence of the torsion angle of the methyl group is not important]?=20 Thanks! John McKelvey ------_=_NextPart_001_01C7B7CB.AA8FD0CB Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Dear John,
 
Try using Opt(GDIIS), it helps in cases where = the potential=20 energy surface is very flat.
 
Best=20 wishes,
Igor=20 Avilov.

From: owner-chemistry#ccl.net=20 [mailto:owner-chemistry#ccl.net]
Sent: lundi 25 juin 2007=20 19:35
To: Igor Avilov
Subject: CCL: G03 optimization = convergence limits

Greetings,

Often when there are freely rotating methyl = groups=20 one can find that the energy and gradients have converged but there is a = large=20 displacement because of the freely rotating or librating methyl group, = and a lot=20 of cpu time can go into getting the methyl group to settle down.  = Does=20 anyone know how to set IOP info to allow a way around this problem = [where=20 convergence of the torsion angle of the methyl group is not important]?=20

Thanks!

John McKelvey
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