The above results were obtained using the SWF model, which, while providing a good description of the shear modulus for hcp solid 4 $_{He}$, significantly underestimates a recent experimental estimate for the SFE, (0 . $^{07}$±0 . 02) mJ / m 2 [24]. In order to explore the possible influence of the SFE value on the dislocation mobility, we repeat the Peierls stress calcula- tions for the case in which the equilibrium dissociation widths of the four dislocation types is reduced by a factor 10, which is the ratio between the experimental and theoretical SFE values. To this end, we apply an additional shear stress component, whose direction in the glide plane is perpendicular to the total Burgers vector of the dislocation. This stress com- ponent, known as Escaig stress [9], does not produce a force on the dislocation as a whole, but mimics a situation with a different SFE value. Using an Escaig stress of 0.4 MPa, we recompute the Peierls stress values for the four dislocations types in the basal plane. The results are shown in the fourth row of Table II. The effect of an increased effective SFE value does not significantly affect the Peierls stress values of the model. This is consistent with earlier PN calculations in metals, in which the Peierls stress was not found to be sensitive to dissociation width [14]. Finally, we examine our results in the context of recent experiments considering the macroscopic behavior of solid $^{4}$He at low temperatures. In the observation[4, 5] of non- classical rotational inertia (NCRI), interpreted as a signature of superfluidity, the crucial role of crystal defects and disorder seems firmly established. Specifically, the behavior of dislocations has attracted a particular interest after the discovery of an unexpected increase of the shear modulus that shows the same temperature and 3 He impurity concentration de- pendence as the original NCRI observations [6–8]. Inspired by the continuum-elasticity based Granato-Lücke theory [25], it has been hypothesized that this stiffening is a consequence of a change of mobility of a network of dislocations. This network is thought to be pinned by 3 He impurities at lowest temperatures, while it becomes mobile under warmer conditions. Analyzing the dislocation mobility results of our model, it is interesting to observe that our lowest Peierls barrier is about 20 times larger than the shear stresses of ∼ 700 Pa reached in recent experiments [7]. This suggests that intrinsic lattice resistance is an essential factor when it comes to the mobility of dislocations on the basal plane in hcp solid 4 $_{He}$. Indeed, at the stress levels reported in these recent experiments, such dislocations would not be expected to be mobile, not even in the absence of any pinning centers. Moreover, it is not expected that the Peierls stress varies significantly as a function of temperature below 0.1 K, 6