Topological studies on IRC paths of X+H2→XH+H reactions

Topological properties of potential energy and electronic density distribution on five reaction paths X+H2→XH+H (X=H, N, HN, H2C, NC) are investigated at the level of UMP2/6–311G(d,p). It has been found that in the region of the reaction paths studied, where B(rc)|s>0 [B(rc)|s is the product of ρ(rc) and ∇2ρ(rc) at the point of reaction process, i.e., B(rc)|s=ρ(rc)∇2 ρ(rc)] is basically the same as the region of V′(s)<0[V′(s) is the second derivative of potential energy with respect to the reaction coordinate, i.e., V′(s)=d2V/ds2], and the point with maximum B(rc)|s is almost coincident with the point of minimum V′(s). It can be concluded from the calculated results that there is a good correlation between the topological properties of potential energy and electronic density distribution along the reaction path. The structure transition state of such collinear reactions may be determined by topological analysis of electronic density. © 1997 John Wiley & Sons, Inc. J Comput Chem18: 1167–1174