Terahertz dielectric response and coupled dynamics of ferroelectrics and multiferroics from effective Hamiltonian simulations

Ferroelectric and multiferroic materials form an important class of functional materials. Over the last twenty years, first-principles-based effective Hamiltonian approaches have been successfully developed to simulate these materials. In recent years, effective Hamiltonian approaches were further combined with molecular dynamics methods to investigate terahertz dynamical properties of various perovskites. With this combination, a variety of ferroelectric and multiferroic materials, including BaTiO_{3}, Ba(Sr,Ti)O_{3}, Pb(Zr,Ti)O_{3}, BiFeO_{3}, and SrTiO_{3} bulks and films have been simulated, which led to the understanding of complex phenomena and discovery of novel effects. In this review, we first provide technical details about effective Hamiltonians and molecular dynamics simulation. Then, we present applications of the combination of these two techniques to different perovskites. Finally, we also briefly discuss possible future directions of this approach.