On the noncollinear magnetic structure of UO2

Recent neutron diffraction measurements on UO$_2$ under high magnetic field predicts a triple-{\bf k} structure associated with a triple-{\bf k} distortion of the oxygen sublattice. We have performed first principles calculations on the magnetic structure of UO$_2$ using the full potential augmented plane wave with local orbitals at ambient conditions. We have investigated two transversal and a longitudinal triple-{\bf k} structures with the experimentally suggested triple-{\bf k} oxygen distortion.