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M. Reticcioli, M. Setvin, X. Hao, P. Flauger, G. Kresse, M. Schmid, U. Diebold, C. Franchini:
"Polaron-Driven Surface Reconstructions";
Physical Review X, 7 (2017), 0310531 - 0310539.

Geometric and electronic surface reconstructions determine the physical and chemical properties of
surfaces and, consequently, their functionality in applications. The reconstruction of a surface minimizes
its surface free energy in otherwise thermodynamically unstable situations, typically caused by dangling
bonds, lattice stress, or a divergent surface potential, and it is achieved by a cooperative modification of the
atomic and electronic structure. Here, we combined first-principles calculations and surface techniques
(scanning tunneling microscopy, non-contact atomic force microscopy, scanning tunneling spectroscopy)
to report that the repulsion between negatively charged polaronic quasiparticles, formed by the interaction
between excess electrons and the lattice phonon field, plays a key role in surface reconstructions. As a
paradigmatic example, we explain the (1 × 1) to (1 × 2) transition in rutile TiO2
ð110Þ.