Parametric evolution, addition of boundstates and generalised Lax   hierarchies
  The connection of the 'time' evolution of the eigenstates of the reflectionless potentials of the Lax hierarchy to the more general case of the 'time' evolution of the eigenstates of the Schroedinger equation for potentials with non-vanishing reflection coefficients is explored. A new hierarchy of functions satisfying 'time' dependent equations is established. 
C. V. Sukumar
math-ph math.MP quant-ph