Multiscale modeling of interaction of alane clusters on Al(111) surfaces: A reactive force field and infrared absorption spectroscopy approach

J. G.O. Ojwang, Santanu Chaudhuri, Adri C.T. Van Duin, Yves J. Chabal, Jean Francois Veyan, Rutger Van Santen, Gert Jan Kramer, William A. Goddard

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Abstract

We have used reactive force field (ReaxFF) to investigate the mechanism of interaction of alanes on Al(111) surface. Our simulations show that, on the Al(111) surface, alanes oligomerize into larger alanes. In addition, from our simulations, adsorption of atomic hydrogen on Al(111) surface leads to the formation of alanes via H-induced etching of aluminum atoms from the surface. The alanes then agglomerate at the step edges forming stringlike conformations. The identification of these stringlike intermediates as a precursor to the bulk hydride phase allows us to explain the loss of resolution in surface IR experiments with increasing hydrogen coverage on single crystal Al(111) surface. This is in excellent agreement with the experimental works of Go [E. Go, K. Thuermer, and J. E. Reutt-Robey, Surf. Sci. 437, 377 (1999)]. The mobility of alanes molecules has been studied using molecular dynamics and it is found that the migration energy barrier of Al2 H6 is 2.99 kcal/mol while the prefactor is D0 =2.82× 10-3 cm2 /s. We further investigated the interaction between an alane and an aluminum vacancy using classical molecular dynamics simulations. We found that a vacancy acts as a trap for alane, and eventually fractionates/annihilates it. These results show that ReaxFF can be used, in conjunction with ab initio methods, to study complex reactions on surfaces at both ambient and elevated temperature conditions.

Original languageEnglish (US)
Article number084509
JournalJournal of Chemical Physics
Volume132
Issue number8
DOIs
StatePublished - 2010

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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