The core structure of screw dislocations with [001] Burgers vector in Mg$_2$SiO$_4$ olivine

Abstract

In this study, we report atomistic calculations of the core structure of screw dislocations with [001] Burgers vector in Mg$_{{2}}$SiO$_{{4}}$ olivine. Computations based on the THB1 empirical potential set for olivine show that the stable core configurations of the screw dislocations correspond to a dissociation in $\lbrace 110\rbrace $ planes involving collinear partial dislocations. As a consequence, glide appears to be favorable in $\lbrace 110\rbrace $ planes at low temperature. This study also highlights the difference between dislocation glide mechanism in $\lbrace 110\rbrace $ versus $(010)$ or $(100)$ for which glide is expected to occur through a locking–unlocking mechanism.

Keywords

• Atomistic simulations
• Crystal plasticity
• Dislocation glide
• Core structure
• Olivine