From owner-nwchem-users@emsl.pnl.gov Fri May 4 02:32:25 2007 Received: from odyssey.emsl.pnl.gov (localhost [127.0.0.1]) by odyssey.emsl.pnl.gov (8.13.8/8.13.8) with ESMTP id l449WOpQ012871 for ; Fri, 4 May 2007 02:32:25 -0700 (PDT) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.13.8/8.13.8/Submit) id l449WO3A012870 for nwchem-users-outgoing-0915; Fri, 4 May 2007 02:32:24 -0700 (PDT) X-Authentication-Warning: odyssey.emsl.pnl.gov: majordom set sender to owner-nwchem-users@emsl.pnl.gov using -f X-Ironport-SG: No_SBRS X-Ironport-SBRS: None X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ao8CAKiaOkaUT1CJ/2dsb2JhbAA X-IronPort-AV: i="4.14,490,1170662400"; d="scan'208"; a="19468547:sNHT21976367" X-DL-MFrom: X-DL-Connect: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.2826 Content-Class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Importance: normal Subject: RE: [NWCHEM] meta gga first derivatives Date: Fri, 4 May 2007 10:32:17 +0100 Message-ID: In-Reply-To: <20070504000202.4zajpvfvmk288484@correoweb.usc.es> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [NWCHEM] meta gga first derivatives thread-index: AceNz06vtNhaWOGbQ4e6HCbnmX5EGQAXPR0A From: "Van Dam, HJJ \(Huub\)" To: , X-OriginalArrivalTime: 04 May 2007 09:32:17.0723 (UTC) FILETIME=[1B5FF8B0:01C78E2F] X-CCLRC-SPAM-report: -4.9 : BAYES_00 X-Scanned-By: MIMEDefang 2.37 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mserv6.dl.ac.uk id l449WIIv026300 Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk Hi Armando, NWChem can certainly compute analytical gradients for meta-GGA's. The comment in the manual stating "However, second derivatives are not available for metaGGAs so in order to calculate geometries, one must use task dft optimize numerical." is admittedly a bit strange. There are two potential explainations for this statement: 1. There was a time when analytical gradients for meta-GGA's were not available but this has been fixed some time ago. Perhaps the manual has not been changed correctly to reflect the new capability. 2. TASK DFT OPTIMIZE will use the stepper optimiser. Stepper uses some hessian information internally. This hessian information might be some starting guess which is updated throughout the optimisation from gradient information becoming available at various points (usually this is good enough for energy minimisations). However the hessian information might be obtained from a previous frequency calculation as well (often needed for saddle point searches). The latter option is of course not available for meta-GGA's. My suggestion would be that you use TASK DFT OPTIMIZE Unless you are looking for saddle points this ought to work. Apart from that it would be good if someone would have a look at the offending statement in the manual and work out what it really is supposed to say. I hope this helps. Best wishes, Huub ======================================================= Huub van Dam (h.j.j.vandam@stfc.ac.uk, +44-1925-603933) ======================================================= -----Original Message----- From: owner-nwchem-developers@emsl.pnl.gov [mailto:owner-nwchem-developers@emsl.pnl.gov] On Behalf Of qoajnv@usc.es Sent: 03 May 2007 23:02 To: nwchem-users@emsl.pnl.gov Subject: [NWCHEM] meta gga first derivatives Dear All: I am not very sure how nwchem is performing meta gga optimizations.  When performing, lets say, a m052x optimization using analytical derivatives, these are computed using the meta GGA or only the GGA part? The manual says that analytical second derivatives are not available but it seems to refer to first derivatives by the context. Best wishes Armando