『Abstract
Recent advances in computer simulation at the atomic scale have
made it possible to probe the structure and behaviour of the cores
of dislocations in minerals. Such simulation offers the possibility
to understand and predict the dislocation-mediated properties
of minerals such as mechanisms of plastic deformation, pipe diffusion
and crystal growth. In this review the three major methods available
for the simulation of dislocation cores are described and compared.
The methods are: (1) cluster-based models which combine continuum
elastic theory of the extended crystal with an atomistic model
of the core; (2) dipole models which seek to cancel the long-range
elastic displacement caused by the dislocation by arranging for
the simulation to contain several dislocations with zero net Burgers
vector, thus allowing a fully periodic super-cell calculation;
and (3) the Peierls-Nabarro approach which attempts to recast
the problem so that it can be solved using only continuum-based
methods, but parameterizes the model using results from atomic-scale
calculations. The strengths of these methods are compared and
illustrated by some of the recent studies of dislocations in mantle
silicate minerals. Some of the unresolved problems in the field
are discussed.
Keywords: computer modelling; dislocations; plasticity; core structure;
deformation.』
Introduction
Background
Cluster models
Coupling elastic and atomistic models
Implementation
Extracting the dislocation energy and structure
Dipole models
Dislocation-dislocation interactions
Peierls-Nabarro model
The generalized stacking fault
Recovering an atomic-scale description
Periclase, halite and related materials
Dislocations in perovskite and post-perovskite structured minerals
Perovskites
Post-perovskite
Forsterite, wadsleyite and ringwoodite
Progress and prospects
Acknowledgements
References