From chemistry-request@ccl.net Thu Jun 2 18:17:28 2005 Received: from prserv.net (asmtp2.prserv.net [32.97.166.52]) by server.ccl.net (8.13.1/8.13.1) with ESMTP id j52MHPZV008414 for ; Thu, 2 Jun 2005 18:17:25 -0400 Received: from [127.0.0.1] (cpe-65-29-74-171.indy.res.rr.com[65.29.74.171]) by prserv.net (asmtp2) with ESMTP id <2005060222172325203te86se> (Authid: jmmckel); Thu, 2 Jun 2005 22:17:23 +0000 Message-ID: <429F8596.3050900 :: attglobal.net> Date: Thu, 02 Jun 2005 17:17:58 -0500 From: John McKelvey User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "T. Daniel Crawford" CC: "S.I.Gorelsky" , Ricardo Oliveira , chemistry :: ccl.net Subject: Re: CCL:TDDFT on G03: negative transition energies References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=failed version=3.0.3 X-Spam-Checker-Version: SpamAssassin 3.0.3 (2005-04-27) on server.ccl.net This comment is strongly tied to the Thouless instability condition [see copious work by Paldus and Cizek in the 60's.] Negative eigenvalues were discussed as a direction in which to improve the reference wavefunction, usually the ground state. Rolf Seeger et. al. placed such code in Gxy for HF wave functions, I believe... John McKelvey T. Daniel Crawford wrote: >It should be noted that, in the TD-DFT framework (which is closely related >to RPA), the response matrix cannot technically have negative eigenvalues. >I would speculate that the eigenvalues reported by the code as negative are >actually pure imaginary. This does indicate an "instability" in the >response matrix, which you could perhaps interpret as a lower-energy state. > >-Daniel > > >On 6/2/05 1:09 PM, "S.I.Gorelsky" wrote: > > > >>>I have done some B3lyp TDDFT calculations on some >>>transition metal complexes and I have obtained some >>>negative excitation energies . Does it make sense or >>>it is an error of the code? Has anyone come across the >>>same problem? >>> >>> >>This means that what you have got as a reference state in your calculation >>is THE EXCITED STATE, and there is at least one lower-energy electronic >>state (the TRUE ground state) at the given level of theory. >> >>Regards, >> >>S. Gorelsky >> >>---------------------------------------------------------------- >> Dr S.I. Gorelsky, Department of Chemistry, Stanford University >> Box 155, 333 Campus Drive, Stanford, CA 94305-5080 USA >> Phone: (650) 723-0041. Fax: (650) 723-0852. >>---------------------------------------------------------------- >> >> >> >> >> >>Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST :: ccl.net >>HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs >> >>use the Web based form from CCL Home Page >> >> >> >> >> >> >> > > >