scheme. They simulated dislocation glide in a stress field which was generated by localized obstacles and found that the effective attack frequency (inverse of waiting time) was indepedent of the choice of segment length and the activation enthalpy was dependent on applied stress and temperature. Mohles and R[ö]{}nnpagel [@Ronnpagel1993_PSS] studied dislocations in a field of obstacles or interacting with obstacle walls. They found that the activation volume for overcoming such obstacles was independent on the spacing of obstacle and the drag coefficient had no influence on waiting time. Their simulation system focused on two dimensional problems [@Ronnpagel1993_PSS; @Mohles1996_CMS]. Hiratani and Zbib [@Hiratani2002_JEMT; @Hiratani2003_JNM] extended the model proposed by R[ö]{}nnpagel et al. [@Ronnpagel1993_PSS] to three-dimensional simulations and used it to simulate dislocation glide through weak obstacles which were represented by stacking fault tetrahedra (SFTs). They found that dislocation motion was obstacle-controlled when the applied stress was below a critical resolved shear stress (CRSS), otherwise drag-controlled [@Hiratani2002_JEMT]; the dislocation line was found to exhibit a self-affine structure as manifested by non-trivial height-difference correlations of dislocation shapes [@Hiratani2003_JNM]. Langevin forces were implemented in different ways in these simulation schemes. Some researchers directly applied Langevin forces on dislocation nodes [@Ronnpagel1993_PSS; @Mohles1996_CMS], while others applied 