Langevin Dynamics/Monte Carlo Simulations of Nanoscale Dielectric Function Modulations of Moire Materials

We have developed a fast and flexible computational scheme to calculate the complex valued, frequency dependent dielectric function of correlated materials. The premise of such a methodology is to use the atomistic crystal structure of materials and designate relatively simple bond length and bond-angle interactions, as well as internal field couplings to accommodate correlation. Once these interactions are appropriated, we simulate systems thin films with periodic boundary conditions via Langevin dynamics under an oscillating external electric field. We validate our method by recreating high-resoltuion infrared near-field experimental results of the dielectric function of perovskite oxide SmNiO₃ . We show quantitative agreement with experimental data concerning the modulation of the nanoscale dielectric changes as a function of hydrogen doping and the prevalence of oxygen vacancies within the sample. We also show representative example of how our methodology can gain us nanoscale insight into the dielectric behavior of Moire patterned two-dimensional transition metal dichalcogenides and compare our results with high-resolution near-field measurements.