Genuine Hydrodynamic Analysis to the 1-D QHD system: Existence, Dispersion and Stability

In this paper we consider the one dimensional quantum hydrodynamics (QHD) system, with a genuine hydrodynamic approach. The global existence of weak solutions with large data has been obtained in [2, 3], in several space dimensions, by using the connection between the hydrodynamic variables and the Schr"odinger wave function. One of the main purposes of the present paper is to overcome the need to postulate the a priori existence of a wave function that generates the hydrodynamic data. Moreover, we introduce a novel functional, related to the chemical potential in the quantum probability density $\rho dx$, which allow us to obtain stability properties for a large class of weak solutions in the finite energy space.