  Object kinetic Montecarlo (OkMC) is a fundamental tool for modeling defect
evolution in volumes and times far beyond atomistic models. The elastic
interaction between defects is classically considered using a dipolar
approximation but this approach is limited to simple cases and can be
inaccurate for large and close interacting defects. In this work a novel
framework is proposed to include "exact" elastic interactions between defects
in OkMC valid for any type of defect and anisotropic media. In this method, the
elastic interaction energy of a defect is computed by volume integration of its
elastic strain multiplied by the stress created by all the other defects, being
both fields obtained numerically using a FFT solver. The resulting interaction
energies reproduce analytical elastic solutions and show the limited accuracy
of dipole approaches for close and large defects.
  The OkMC framework proposed is used to simulate the evolution in space and
time of self-interstitial atoms and dislocation loops in iron. It is found that
including the anisotropy has a quantitative effect in the evolution of all the
type of defects studied. Regarding dislocation loops, it is observed that using
the "exact" interaction energy result in higher interactions than using the
dipole approximation for close loops.
