A channel for dimer flipping on the Si(001) surface

A mechanism of dimer flipping on the Si(001) surface has been investigated by means of ab initio pseudopotential calculations. These studies clearly d emonstrate a tied flipping behavior of two consecutive dimers: the buckling of adjacent outer dimers becomes stronger while two inner dimers switch th eir orientation, which facilitates the inner dimer flipping by relieving th e sublayer strain. Contrary to popular speculation, in most cases, the dime rs undergo thermal fluctuations between two unequal energy minima. Hence, a clean Si(001) surface can preserve the 2 x anticorrelation of dimer buckli ng along a row at room temperature. (C) 2000 Elsevier Science B.V. All righ ts reserved.