Ab initio explanation of the apparent violation of detailed balance for H2 adsorption/desorption from Si(100)

Michelle R. Radeke, Emily A. Carter

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25 Scopus citations


The experimentally observed apparent violation of detailed balance in the adsorption and desorption of H2 on Si(100)-2 × 1 is explained via a dihydride intermediate that can be accessed via two different transition states, as found by complete active space self-consistent field/multireference single and double excitation configuration interaction (CASSCF/MRSDCI) calculations. Our calculations explain the low sticking probability by predicting an early symmetric transition state to adsorption with a high barrier. We predict that desorption, on the other hand, occurs through an asymmetric transition state and find excellent agreement between our calculated barrier to desorption and experimental values. For the asymmetric transition state we calculate a small barrier to adsorption, however, we suggest that impinging H2 seldom sees this orientationally constrained late transition state to adsorption, explaining the apparent violation of detailed balance.

Original languageEnglish (US)
Pages (from-to)L289-L294
JournalSurface Science
Issue number1-3
StatePublished - Jun 1 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


  • Ab initio quantum mechanical methods and calculations
  • Adsorption kinetics
  • Hydrogen
  • Silicon
  • Solid-gas interfaces
  • Thermal desorption


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