A finite-temperature dynamic coupled atomistic/discrete dislocation method

摘要: A method for simultaneously thermostatting an atomistic region and absorbing energetic pulses impinging on the atomistic/continuum interface from is developed to operate within framework of coupled atomistic/discrete dislocation method. The approach inserts additional Langevin damping term a random force into equations motion atoms in 'stadium' boundary near atom/continuum interface, with coefficient ramped linearly over width region, as suggested by Holian Ravelo. remaining interior atom dynamics are computed using standard MD algorithm no artificial or thermostatting. continuum deformations static FEM updated stochastically time scales comparable Debye frequency time-averaged displacements at thereby providing evolution that tracks deformation. evaluated studying ability system: (i) equilibrate inner desired temperature under conditions external internal loading, (ii) produce proper canonical thermal fluctuations (iii) absorb deformation initiated incident upon boundary. With optimal maximum approximately 1/2 frequency, stability attained values very close target temperature. variance agrees well expectation various temperatures. For same parameters low temperature, high-energy propagate unimpeded up stadium then completely damped out measurable reflections. At higher temperatures, total energy make analyses difficult, but achieved limits noise system while observation time-dependent shows observable