  In this paper, we introduce a new kind of spin switch based on a joint system
of copper phthalocyanine (CuPc) and C59N. Using density functional theory, we
investigate the total magnetic moment of this system when gradually changing
the interval distance between two molecules. The spin hopping happens during
the critical distance with very low energy. This phenomenon shows a possible
reality of reversible spin switch by external control of the interval distance.
With orbital analysis and electron transfer consideration, the form of C59N+-
CuPc- ion pair support this spin hopping phenomenon.
