Fictitious excitations in the classical Heisenberg antiferromagnet on   the kagome lattice
  Using an advanced Monte Carlo algorithm and high precision spin dynamics simulation, we investigated the dynamical behavior of the Heisenberg antiferromagnet on a kagome lattice at extremely low temperatures. We demonstrate that the detection and correct identification of propagating excitations depends crucially on the choice of coordinates and we show how modes are displaced in Fourier space if a single, global Cartesian coordinate system is chosen. 
Stefan Schnabel and David P. Landau
cond-mat.str-el cond-mat.stat-mech