Soliton excitations and interaction in alpha helical protein with interspine coupling in modified nonlinear Schrödinger equation**Project supported by the National Natural Science Foundation of China (Grant Nos. 11874324 and 11705164), the Natural Science Foundation of Zhejiang Province of China (Grant Nos. LY17A040011, LY17F050011, and LR20A050001), the Foundation of “New Century 151 Talent Engineering” of Zhejiang Province of China, and the

Abstract

The three-coupling modified nonlinear Schrödinger (MNLS) equation with variable-coefficients is used to describe the dynamics of soliton in alpha helical protein. This MNLS equation with variable-coefficients is firstly transformed to the MNLS equation with constant-coefficients by similarity transformation. And then the one-soliton and two-soliton solutions of the variable-coefficient-MNLS equation are obtained by solving the constant-coefficient-MNLS equation with Hirota method. The effects of different parameter conditions on the soliton solutions are discussed in detail. The interaction between two solitons is also discussed. Our results are helpful to understand the soliton dynamics in alpha helical protein.