This work examines the applicability of a specific force field model – ANI-2x – to the polymer polyphenylene sulfide. The order of the actions taken is given and, as a result, the radial distribution function of sulfur atoms in systems with different temperatures is compared. It was shown that qualitatively the ANI-2x field correctly describes the situation during the transition through the glass transition temperature.

Keywords: poluphenylene sulfide, classic molecular dynamics, machine learning, force field, potential, polymer, computer simulation, model

Mathematical modeling of processes in the crystal structures of the Gunn diode and modeling of the operation of the diode itself in various electrical circuits are relevant for monitoring the operation of electronic devices The paper investigates the effect of low-frequency pickups in the power supply circuit of the Gunn diode on the Fourier spectrum of the generated microwave signal. To study the processes of formation and motion of a domain in a crystal structure, the local field model of the Gunn diode is used, based on the assumption that the average drift velocity of electrons depends on the instantaneous value of the electric field, and the diffusion coefficient does not depend on the applied electric field. A serial circuit for switching on a diode with a power source and a resistive load is simulated. As a result of the simulation of the program, the distribution of stresses inside the crystal along its length at a selected moment of time is obtained; graphs of the movement of domains are plotted based on these data. Based on the data obtained, a Fourier transform is performed, and the resulting spectrum is constructed. The correctness of the program operation is confirmed by the spectrum obtained by the 3A703B diode on the S4-27 spectrum analyzer. The shape of the inhomogeneities in the crystal lattice, given the same width, does not affect the formation of domains. Rectangular, parabolic and gradient functions of dopant concentration variation are investigated. If the function changes more smoothly, then the maximum amplitude of the domain strengths will be greater, but the domain will take a little longer to form. The resulting model can be used to calculate fields with different loads in an electrical circuit.

Keywords: Gunn diode, microwave, simulation of physical processes, Fourier spectrum, radar systems