Gaussian wave packet solution of the Schrodinger equation in the   presence of a time-dependent linear potential
  We argue that the way to get the general solution of a Schrodinger equation in the presence of a time-dependent linear potential based on the Lewis-Riesenfeld framework is to use a Hermitian linear invariant operator. We demonstrate that the linear invariant proposed in p and q is an Hermitian operator which has the Gaussian wave packet as its eigenfunction. 
M. Maamache and Y. Saadi