  We report on theoretical investigation of the magnetization reversal in
two-dimensional arrays of ferromagnetic nano-particles with parameters of
cobalt. The system was optimized for achieving the lowest coercivity in an
array of particles located in the nodes of triangular, hexagonal and square
grids. Based on the numerical solution of the non-stochastic
Landau-Lifshitz-Gilbert equation we show that each particle distribution type
is characterized with a proper optimal distance, allowing to lower the
coercivity values for approximately 30% compared with the reference value
obtained for a single nano-particle. It was shown that the reduction of
coercivity occurs even if the particle position in the array is not very
precise. In particular, the triangular particle arrangement maintained the same
optimal distance between the particles under up to 20% random displacements of
their position within the array.
