ELECTRONIC-STRUCTURE AND POSSIBLE MECHANISM OF POTASSIUM INDUCED PROMOTION OF OXIDATION OF SI(001)2X1

Local density total energy structural and electronic property studies using molecular cluster models with up to 98 atoms reveal that on coadsorption with O2: (i) K relaxes away from the Si surface with the KSi bond length increasing by ∼ 5% (and hence is more easily desorbed after catalytic oxidation); (ii) the O2 position and bond length are unchanged with the O2 more tightly bound to the Si surface (which explains the increased sticking coefficient); and (iii) additional charge transfer from K to the O2 antibonding orbitals and reduced O2 vibrational frequency (which help promote dissociation). © 1990.