Item
Paterson, Martin J.
Bearpark, Michael J. Robb, Michael A. Blancafort San JosÃ©, LluÃs 

We present a method for analyzing the curvature (second derivatives) of the conical intersection hyperline at an optimized critical point. Our method uses the projected Hessians of the degenerate states after elimination of the two branching space coordinates, and is equivalent to a frequency calculation on a single BornOppenheimer potentialenergy surface. Based on the projected Hessians, we develop an equation for the energy as a function of a set of curvilinear coordinates where the degeneracy is preserved to second order (i.e., the conical intersection hyperline). The curvature of the potentialenergy surface in these coordinates is the curvature of the conical intersection hyperline itself, and thus determines whether one has a minimum or saddle point on the hyperline. The equation used to classify optimized conical intersection points depends in a simple way on the first and secondorder degeneracy splittings calculated at these points. As an example, for fulvene, we show that the two optimized conical intersection points of C2v symmetry are saddle points on the intersection hyperline. Accordingly, there are further intersection points of lower energy, and one of C2 symmetry  presented here for the first time  is found to be the global minimum in the intersection space  
http://hdl.handle.net/2072/116718  
eng  
American Institute of Physics  
Tots els drets reservats  
Algorismes
EnllaÃ§os quÃmics Energia de superfÃcie Estructura molecular OptimitzaciÃ³ matemÃ tica Algorithms Chemical bonds Mathematical optimization Molecular structure Surface energy 

The curvature of the conical intersection seam: an approximate secondorder analysis  
info:eurepo/semantics/article  
Recercat 