From owner-nwchem-users@emsl.pnl.gov Mon Feb 19 12:46:49 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 l1JKkmNu004029 for ; Mon, 19 Feb 2007 12:46:49 -0800 (PST) Received: (from majordom@localhost) by odyssey.emsl.pnl.gov (8.13.8/8.13.8/Submit) id l1JKkmH0004028 for nwchem-users-outgoing-0915; Mon, 19 Feb 2007 12:46:48 -0800 (PST) X-Authentication-Warning: odyssey.emsl.pnl.gov: majordom set sender to owner-nwchem-users@emsl.pnl.gov using -f X-Possible-Spoof: True X-IronPort-AV: i="4.14,191,1170662400"; d="scan'208"; a="13821740:sNHT129543946" X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Subject: RE: [NWCHEM] turn off symmetry Date: Mon, 19 Feb 2007 12:46:45 -0800 Message-ID: <37275E1A43F1EC4C938AEFA1CFFAA0E301612BB6@EMAIL02.pnl.gov> In-Reply-To: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [NWCHEM] turn off symmetry Thread-Index: AcdUNa9tFcS53QjDQKyCjmZnWz4GAgAA1GnAAAtz3gA= References: From: "Vorpagel, Erich R" To: "Van Dam, HJJ \(Huub\)" , "simon" , X-OriginalArrivalTime: 19 Feb 2007 20:46:46.0354 (UTC) FILETIME=[11FD8320:01C75467] Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by odyssey.emsl.pnl.gov id l1JKkl1k004025 Sender: owner-nwchem-users@emsl.pnl.gov Precedence: bulk Greetings Simon, Another way to turn off symmetry is to add the keyword "noautosym" to the geometry line. For example geometry noautosym O 0 0 0 H 0 1.430 1.107 H 0 -1.430 1.107 end Regards, Erich R. Vorpagel, Ph.D. Chief Scientist Manager Computational Grand-Challenge and Pilot Projects MSCF Visualization and User Services Group Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory P. O. Box 999, MS: K8-91 3335 Q Ave. Phone: 509-376-0751 Richland, WA 99352 FAX: 509-376-0420 Email: erich.vorpagel@pnl.gov Web: http://mscf.emsl.pnl.gov/ -----Original Message----- From: owner-nwchem-users@emsl.pnl.gov [mailto:owner-nwchem-users@emsl.pnl.gov] On Behalf Of Van Dam, HJJ (Huub) Sent: Monday, February 19, 2007 7:32 AM To: simon; nwchem-users@emsl.pnl.gov Subject: RE: [NWCHEM] turn off symmetry Hi Simon, To turn the symmetry off in your calculation use the symmetry keyword in the geometry block but specify the point group C1. For example the geometry below could be used to do a calculation on the water molecule without symmetry. Geometry symmetry c1 O 0 0 0 H 0 1.430 1.107 H 0 -1.430 1.107 end I have no idea whether turning symmetry off will solve your problem though. Of course if the denegeneracy persists your MP2 result is undefined. Is it really necessary to do MP2 at that geometry? Best wishes, Huub ========================================================== Huub van Dam (h.j.j.vandam@dl.ac.uk, +44-1925-603933) ========================================================== -----Original Message----- From: owner-nwchem-developers@emsl.pnl.gov [mailto:owner-nwchem-developers@emsl.pnl.gov] On Behalf Of simon Sent: 19 February 2007 14:27 To: nwchem-users@emsl.pnl.gov Subject: [NWCHEM] turn off symmetry Hello, I have a poor convergence problem in a MP2 calculation due a degeneracy between my HOMO and my LUMO. Here is the error message. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Warning - the HOMO and LUMO are degenerate and you are using symmetry. This can lead to non-variational energies and poor convergence. Modify the initial guess, or use an open-shell wavefunction, or turn off symmetry. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! My input coordinates were optimized with DFT and I tried also HF optimized coordinates but I still got this problem. My system is not supposed to be open-shell so I didn't not try it. Finally I didn't find a way to turn off symmetry in the manual. Does somebody have a clue what I could try? Is it possible to turn off symmetry in a MP2 calculation? Thanks in advance, Simon Pierrefixe Vrij Universiteit.