Our implementation and validation of the THB1 potential library to a well parallelized open-source molecular mechanics code (LAMMPS, Scandia National Lab.) opens door for better understanding of dislocation cores of forsterite. Using this potential library we were able to analyse screw dislocations of Burgers vector [100] and [001]. The dislocation core spreading of [100] dislocation on (010) plane emphasised the importance of [100](010) slip system. On the other hand, [001] dislocation form a narrow compact core, glide analysis of this core reveal a possible locking-unlocking mechanism for dislocation motion. Also this work confirms the occurrence of dilatation state within the [100] screw core, which may have strong implication for activation of [100] dislocation at higher pressure conditions. And we believe this methodology can be further extended to study the dislocation core properties at different pressure.

Trace of strain tensor mapped around the [100] dislocation core region and calculated from the O sub-lattice. Positive values for the trace of the strain tensor quantify the dilatation of the dislocation core.

For more: S. Mahendran, P. Carrez, S. Groh & P. Cordier (2017) Dislocation modelling in Mg₂SiO₄ forsterite: an atomic-scale study based on the THB1 potential, Modelling and Simulation in Materials Science and Engineering 25(5), 054002, doi: 10.1088/1361-651X/aa6efa Open access .