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We investigate magnetic ordering in the non-collinear antiferromagnet
CrB₂. In this bulk system honeycomb layers of B alternate with
triangular layers of Cr, in which a mixture of ferromagnetic and
antiferromagnetic exchange gives rise to an incommensurate ground state
spin spiral. We provide an ab initio description on the footing of both
the Linear Muffin-Tin Orbital (LMTO) and the Screened
Korringa–Kohn–Rostoker (SKKR) methods using the Generalized Gradient
Approximation (GGA). By extracting parameters of a spin model directly
from the electronic structure we can assess the strongly non-collinear
spin texture in terms of mean field theory and spin dynamics
simulations. Comparing the spin models obtained with ferromagnetic and
paramagnetic reference states we conclude that the latter gives a more
realistic overall description of the system, especially with regards to
the Néel temperature. The wave vector of the obtained ground state
estimate provided by LMTO and SKKR are in excellent agreement with each
other, however, lower in magnitude than seen in experiment.