From owner-chemistry:~at~:ccl.net Fri Jun 13 04:17:01 2014 From: "Mariusz Radon mariusz.radon~~gmail.com" To: CCL Subject: CCL: Spin Delocalization/Localization using two different functionals Message-Id: <-50203-140613041346-30039-8iaFO7EhnfK6uSQkHaYeWQ+/-server.ccl.net> X-Original-From: Mariusz Radon Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Date: Fri, 13 Jun 2014 10:13:35 +0200 MIME-Version: 1.0 Sent to CCL by: Mariusz Radon [mariusz.radon~~gmail.com] On 06/13/2014 01:09 AM, Kerry Jeffry Wrighton kerry.wrighton%usach.cl wrote: > Sent to CCL by: "Kerry Jeffry Wrighton" [kerry.wrighton*usach.cl] > Dear CCL team > > I have a question related to equilibrium geometries using B3LYP (hybrid) and > BP86 (GGA) functionals using the same basis set for both methods (TZV). I have > optimized the structure of a hexavanadium cluster, which contains 4 V(IV) and > 2 V(V) atoms. When I used the B3LYP functional, spin density is perfectly > localized over 4 V(IV) atoms. In the case of the BP86 functional the spin > density is full delocalized over the 6 V atoms. In both cases, the structures > are validated through the frequency analysis and comparison with bond > distances of crystallographic data. Why did it happen? > > Best Regards > > Kerry Wrighton-Araneda > Dear Kerry: It is a known tendency of pure functionals (like BP86) to overestimate an electron delocalization due to the self interaction error. This error can be compensated, in part, by mixing an approximate exchange functional with the exact exchange (like in B3LYP). See for instance [DOI: 10.1021/ct800531s]. It is thus perfectly understandable that introducing the exact exchange in B3LYP, as compared with BP86, leads to the more localized unpaired electrons. Recently I reported the similar behavior of these two functionals for a tetravanadium cluster [DOI: 10.1016/j.inoche.2013.12.034 + Supporting Information]. Best regards, Mariusz -- Dr Mariusz Radon, Ph.D. Coordination Chemistry Group Faculty of Chemistry Jagiellonian University ul. Ingardena 3, 30-060 Krakow, Poland http://www2.chemia.uj.edu.pl/~mradon