  We study charmonia in electromagnetic and rotational fields in the frame of a
potential model. Different from the temperature field which is isotropic and
leads to the well-known charmonium dissociation, the electromagnetic and
rotational fields break down the radial symmetry, and the competition between
strong interaction and electromagnetic and rotational interaction in the
direction of Lorentz force makes the charmonia transit from an isotropic bound
state of strong interaction with positive binding energy to an anisotropic
bound state of electromagnetic and rotational interaction with negative binding
energy. The transition seems possible to be realized in high energy nuclear
collisions.
