Integration of a defocusing nonlinear Schrödinger equation with additional terms

The inverse spectral problem method is used to integrate the nonlinear Schrödinger equation with some additional terms in the class of infinite-gap periodic functions. We reveal the evolution of spectral data for a periodic Dirac operator whose coefficients solve the Cauchy problem for a nonlinear Schrödinger equation with some additional terms. Several examples are given to illustrate the algorithm described in the paper.