I. Assessment of switching by hydrogen transfer for pyrazole model

Potential energy surfaces of N,N-hydrogen migration of pyrazole and 5-methyl pyrazole for the ground and triplet states were calculated by the ab initio molecular orbital methods. All potential energy surfaces for the N.N-hydrogen shift have high energy barriers. The occurrence of the structural change indispensable to the switching function is doubtful for pyrazole and 5-methyl pyrazole. The switching mechanism by N,N-hydrogen migration was also studied on the basis of a simple model. The possibility of the switching function was found at the n2 7' x2 excitation with the relaxation of the CNN angle.