Non-dispersive wavepacket solutions of the Schrodinger equation
  The free Schrodinger equation has constant velocity wavepacket solutions \psi_{\bf v} of the form \psi= f({\bf r} - {\bf v}t) e^{- i m c^2 t / 2}. These solutions are eigenvectors of a momentum operator {\bf \tilde p} which is symmetric in a positive definite scalar product space. We discuss whether these \psi_{\bf v} can act as basis states rather than the usual plane wave solutions. 
Shaun N. Mosley