title: Unique dynamic appearance of a Ge-Si ad-dimer on Si(001).
abstract: We carry out a comparative study of the energetics and dynamics of Si-Si, Ge-Ge, and Ge-Si ad-dimers on top of a dimer row in the Si(001) surface, using first-principles calculations. The dynamic appearance of a Ge-Si dimer is distinctively different from that of a Si-Si or Ge-Ge dimer, providing a unique way for its identification by scanning tunneling microscopy (STM). Its "rocking" motion, observed in STM, actually reflects a 180 degrees rotation of the dimer, involving a piecewise-rotation mechanism. The calculated energy barrier of 0.74 eV is in good agreement with the experimental value of 0.82 eV.
authors.affiliation: Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Lu
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.forename: C Z
authors.initials: CZ
authors.lastname: Wang
authors.forename: X R
authors.initials: XR
authors.lastname: Qin
authors.forename: B S
authors.initials: BS
authors.lastname: Swartzentruber
authors.forename: M G
authors.initials: MG
authors.lastname: Lagally
authors.forename: K M
authors.initials: KM
authors.lastname: Ho