The intersection seam between the two lowest (1)A' states of ozone has
been determined. The potential energy surfaces and the seam are calcu
lated and discussed in perimetric coordinates which exhibit the full t
hree-dimensional symmetry. The seam is shown to form a closed curve wh
ich crosses the C-2v-restricted coordinate planes at six points. Three
of these correspond to the previously determined intersection, the st
arting point of the present search. The other three correspond to high
ly repulsive regions on the potential energy surface where two atoms a
pproach each other to within two-thirds of the O-2 bond length. At the
former three points both states have (1)A(1) symmetry, but at the lat
ter three points one state has (1)A(1) symmetry whereas the other has
B-1(2) symmetry. Consequently, there exist three additional branches o
f the intersection seam between these two states. Each of these branch
es lies entirely in one C-2v-restricted coordinate plane and connects
to the previously discussed C-s-seam at one point. The existence of a
further intersection seam is established. A novel method for determini
ng intersection points is described.