Magnetism and vibrations in the phase of oxygen

Abstract: Sandwiched between a set of magnetic phases at lower pressure, and a non magnetic phase at higher pressure, the magnetic state of phase of oxygen has so far been elusive, together with its crystal structure. Neutron diffraction data indicate an absence of antiferromagnetism, but do not exclude a ferromagnetic order. The recent refinement of the internal atomic positions from single-crystal diffraction finally provides us with a correct structural model to study the possible occurrence of a magnetic ground state. By employing non-collinear spin-polarized density-functional theory we show that the ground state of -O2 is non magnetic. We also calculate vibrational spectra and show that -O2 possesses an additional vibron mode with large Raman cross section, not seen in experiments yet. [Copyright &y& Elsevier]