The non-linear solutions of the Modified Korteweg-de Vries (MKdV) equations
travel on the nuclear surface of medium-heavy nuclei and generate highly d
eformed shapes. The cnoidal and soliton solutions provide the existence of
rotons as large amplitude collective oscillations. The dynamics is based on
the nonlinear equations and Hamiltonian of a realistic liquid drop model (
LDM). The antisoliton solutions are obtained through a general formulation
of nonrelativistic quantum mechanics in terms of density and current operat
ors. The quantum averaging of the antisoliton pail rotation describes symme
tric or asymmetric fission modes. The nuclear asymmetry near the scission p
oint seems to be in qualitative agreement with the general shapes considere
d in all other phenomenological fission models.