Variational principle and periodic solution of the Kundu-Mukherjee-Naskar equation

Kundu-Mukherjee-Naskar equation admits many attractive solitary wave solutions as discussed by Biswas et al. (Results in Physics, Volume16, 2020, 102850). This paper shows that a variational formulation can be established by the semi-inverse method, and its periodic solution is elucidated. This short note sheds a light on new research frontiers of solitary wave theory.