From chemistry-request@ccl.net Thu Sep 9 12:06:56 2004 Received: from smtp.nist.gov (rimp1.nist.gov [129.6.16.226]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id i89H6tIx030061 for ; Thu, 9 Sep 2004 12:06:55 -0500 Received: from postmark.nist.gov (pullyou.nist.gov [129.6.16.93]) by smtp.nist.gov (8.12.10/8.12.10) with ESMTP id i89HGMNR027713 for ; Thu, 9 Sep 2004 13:16:22 -0400 Received: from SILYL.nist.gov (h183164.nist.gov [129.6.183.164]) by postmark.nist.gov (8.12.5/8.12.5) with ESMTP id i89HFsZ7028971 for ; Thu, 9 Sep 2004 13:15:54 -0400 (EDT) Message-Id: <5.0.0.25.2.20040909130816.00aec088{at}mailserver.nist.gov> X-Sender: rdj3{at}mailserver.nist.gov X-Mailer: QUALCOMM Windows Eudora Version 5.0 Date: Thu, 09 Sep 2004 13:15:37 -0400 To: CHEMISTRY{at}ccl.net From: Russ Johnson Subject: Re: CCL:dipoles In-Reply-To: <200409091428.QAA09629{at}web1.ulb.ac.be> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-NIST-MailScanner: Found to be clean X-MailScanner-From: russell.johnson{at}nist.gov X-Spam-Status: No, hits=2.0 required=7.5 tests=IMPRONONCABLE_1,MAILER_VERSION autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net The NIST Computational Chemistry Comparison and Benchmark Database (http://srdata.nist.gov/cccbdb) has a page for comparing experimental and calculated dipoles (section IV.E.1). It has 162 molecules with experimental dipoles. While it doesn't have the 6-31++G** basis set it does have both 6-31G* and 6-31+G**. For BLYP, B3LYP, B3PW91, mPW1PW91, and PBEPBE the rms differences improve on going to the larger basis set. At 16:28 2004/09/09 +0200, you wrote: >Dear all, >Is there anyone who knows why dipole moments calcultaed with a 6-31++G** basis set are worser (deviate more from experimental values) than those calculated with a 6-31G* basis set? >I used B3LYP as calculation method and I tested it for 10 molecules. >Thank you in advance for help, >Best regards, Goedele > >Drs. Goedele Roos Dr. Russell D. Johnson III Research Chemist National Institute of Standards and Technology Computational Chemistry Group 100 Bureau Drive, Stop 8380 Gaithersburg, MD 20899-8380 voice 301+975-2513 fax 301+869-4020 email: russell.johnson{at}nist.gov