Transition from Mn(4+) to Mn(3+) induced by surface reconstruction at λ-MnO(2)(001).
Structural and electronic properties of the λ-MnO(2)(001) surface are investigated applying density functional theory approach. The calculations show that all Mn ions at unreconstructed smooth surface preserve the +4 oxidation state observed in the bulk. Upon the λ-MnO(2)(001) reconstruction, one fourth of Mn ions at the surface undergo a change of the oxidation state from +4 to +3, although the reconstruction does not change the Mn coordination number with oxygen. This is accompanied with the filling of initially empty 3d(z(2) ) states localized on cations with one electron denoted by two neighboring O atoms. Although the reconstruction leads to an energy gain of 0.04 eV per surface unit cell, it is not a spontaneous process since it proceeds with an activation energy of 0.12 eV.
Department of Physics, Jiangxi Normal University, Nanchang 330022, China. cyouyang@jxnu.edu.cn
C Y
CY
Ouyang
Z
Z
Sljivancanin
A
A
Baldereschi