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.