The fourth order nonlinear Schrodinger limit for quantum Zakharov system
  This paper is concerned with the quantum Zakharov system. We prove that when the ionic speed of sound goes to infinity, the solution to the fourth order Schrodinger part of the quantum Zakharov system converges to the solution to quantum modified nonlinear Schrodinger eqaution. 
Yung-Fu Fang, Chi-Kun Lin, and Jun-ichi Segata
math.AP