First principles study of ortho–para H₂ conversion on the O₂(0.25 ML)/Ag(111) system
2012
Kunisada, Yuji | Nakanishi, Hiroshi | Diño, Wilson Agerico | Kasai, Hideaki
We investigated the ortho–para (o–p) H₂ conversion on the O₂/Ag(111) system, combining first principles calculations based on spin-polarized density functional theory with perturbative calculations. In this study, we calculated the o–p H₂ conversion rate, using the standard Fermi's Golden Rule and compared the contribution efficacy of the magnetic dipole interaction and the Fermi contact interaction. The calculated o–p H₂ conversion times induced by the magnetic dipole interaction and by the Fermi contact interaction, corresponding to the reciprocal of the o–p H₂ conversion rates, are in the orders of 10⁰–10³ s and 10⁰–10⁶ s, respectively. In comparison with the o–p H₂ conversion time of 610 s on clean Ag surfaces, these results indicate that the magnetic dipole interaction and the Fermi contact interaction enhance the o–p H₂ conversion in the vicinity of O₂. In addition, the magnetic dipole interaction and the Fermi contact interaction can be separately observed with the different distances between H₂ and O₂.
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