Search for Conical Intersection points (CI) by Newton Trajectories

% {for the Allyl Radical Ring Closure}

by
Wolfgang Quapp, {1}  Josep Maria Bofill {2}  and Marc Caballero {3}

{1} Mathematisches Institut, Universit"at Leipzig,
    PF 100920, D-04009 Leipzig, Germany
    email: quapp@uni-leipzig.de   Tel.: +49-341-97321-53 
    Fax: +49-341-97321-99  
    Web: http://www.mathematik.uni-leipzig.de/MI/~quapp

{2} Departament de Qu'imica Organica, Universitat de Barcelona,
    c/Mart'i i Franqu'es, 1, 08028 Barcelona, Spain;
 and Institut de Qu'imica Teorica i Computacional, Universitat de
    Barcelona (IQTCUB), c/Mart'i i Franques, 1, 08028 Barcelona
{3} Departament de Qu'imica F'isica, Universitat de Barcelona,
    c/Mart'i i Franqu'es, 1, 08028 Barcelona, Spain;
 and Institut de Qu'imica Teorica i Computacional, Universitat de
  Barcelona (IQTCUB), c/Mart'i i Franqu\{e}s, 1, 08028 Barcelona

 Subject area: general interest in theoretical chemistry 

abstract 

Recently, valley-ridge inflection points on the potential energy surface 
for the ring opening of the cyclopropyl radical have been determined using 
Newton trajectories (NT) 
[Quapp, Bofill, Aguilar-Mogas (2011) Theor Chem Acc 129:803].
This letter is the report about the utilization of NTs for the search for
conical intersection (CI) points. These points play a main role in the 
understanding of intersections of different electronic surfaces which open
the door for photochemical reactions. We explain the reason why Newton 
trajectories can find CI points, and report a CI seam on the CASSCF(3,3) 
surface of the allyl radical ring closure.


in CPL 2012