Analysis of the derivative coupling vector for the 1,2 (2)A ' states of H-3

Near the conical intersection for the 1,2 (2)A' states of H-3 the derivativ e coupling vector is calculated and analyzed on the plane of internal coord inates, (U,V) or its polar coordinates (S, theta), based on the squares of the internuclear distances. It is shown that in the vicinity of the conical intersection the derivative coupling vector behaves like theta /2S, which is responsible for the sign changes of the real-valued electronic wave func tion when the nuclear configuration traverses a closed path enclosing a con ical intersection. The analytic property of the wave functions is studied a nd especially the observation of the sign change in the configuration state function (CSF) coefficients of the real-valued electronic wave functions i s demonstrated.