DYNAMICAL JAHN-TELLER EFFECT AND BERRY PHASE IN POSITIVELY CHARGED FULLERENES - BASIC CONSIDERATIONS

We study the Jahn-Teller effect of positive fullerene ions C-2(60)+ an d C-1(60)2+. The aim is to discover if this case, in analogy with the negative ion, possesses a Berry phase or not, and what are the consequ ences on dynamical Jahn-Teller quantization. Working in the linear and spherical approximation, we find no Berry phase in C-1(60)2+, and pre sence/absence of Berry phase for coupling of one L=2 hole to an L=4/L= 2 vibration. We study in particular the special equal-coupling case (g (2)=g(4)), which is reduced to the motion of a particle on a five-dime nsional sphere. In the icosahedraI molecule, the final outcome assesse s the presence and/or absence of a Berry phase of pi for the h(u) hole coupled to G(g)/H-h vibrations. Some qualitative consequences on grou ndstate symmetry, low-lying excitations, and electron emission from C- 60 are spelled out.