Subquadratic wavenumber dependence of the structural relaxation of supercooled liquid in the crossover regime

摘要: As a liquid is progressively supercooled toward its glass transition temperature, an intriguing weakening of the wavenumber (q) dependence structural relaxation time τ(q) in intermediate-to-large q limit observed both experiments and simulation studies. Neither continuous Brownian diffusive dynamics nor discontinuous activated events can alone explain anomalous dependence. Here we use our recently developed theory that unifies mode coupling for dynamics, with random first order treatment motion as nucleationlike instanton process to understand density relaxation. The predicted smooth change mechanism from activated, crossover regime, wavevector dependent appears be responsible subquadratic, almost linear, time.