From owner-chemistry@ccl.net Tue May 30 07:39:00 2006 From: "Godefroid GAHUNGU ggahungu+/-yahoo.fr" To: CCL Subject: CCL:G: Exchange coupling in triradicals within C3 symmetry Message-Id: <-31863-060529184915-25894-up8sq4Sww+3xLge/1mgXww++server.ccl.net> X-Original-From: "Godefroid GAHUNGU" Date: Mon, 29 May 2006 18:49:13 -0400 Sent to CCL by: "Godefroid GAHUNGU" [ggahungu++yahoo.fr] Dear all, My greetings first. In my actual work, I am interested in calculating the exchange coupling (J) values for organic triradicals systems within C3 symmetry. Because of the more extensive electronic degeneracy, ab initio modeling of triradicals seems to be even more complicated than that of diradicals. So far, it is proposed that, from a methodological perspective, a multiconfigurational method should be employed when the triradical orbitals are nearly degenerate, and that Spin-Flipping approach (SF) can be employed to describe triradicals. Through this message, I would like to ask for an assistance about how to proceed, from the geometry optimization (since no crystal structures are not available yet) to the calculation of the J value (let me tell you that there is no experimental J values are available yet). As computational resources, I am intending to use Gaussian 98 or 03 packages, but also have an already installed ORCA program. Would you like to provide me with some details about which appropriate key words to be used within ORCA input files? Thanks ahead for your coming assistance. GAHUNGU Godefroid (Ph.D student) E-mail: ggahungu|*|yahoo.fr Northeast Normal University Chemistry Department Renmin Street, 5268 Changchun-Jilin (PR. China)