Surface soft phonon and the root3 x root3 <--> 3 x 3 phase transition in Sn/Ge(111) and Sn/Si(111)

Ruben Perez, Jose Ortega, Fernando Flores

Density Functional Theory (DFT) calculations show that the reversible Sn/Ge(111) $\sqrt{3}\times \sqrt{3}\leftrightarrow 3\times 3$ phase transition can be described in terms of a s…