文献是这样说的:The surface density (2.08 X 1015 total
atoms/cml = 1.56 X 1015 0 atoms/cmz + 0.S2X 1015 Ti
atoms/cml) is calculated by assuming the bulk termination
model of the (I X I) surface with three oxygen atoms
(two in-plane and one bridging) and one Ti atom per unit
cell