Electrostatics and reactivity of surface defects on Si(111)-(2 X 1)

Krisztina Kádas, G. Náray-Szabó

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We calculated the electrostatic field (the gradient of the molecular electrostatic potential) near steps and corners on the Si(111)-(2 X 1) surface using the semiempirical AM1 molecular orbital method. Calculations on appropriate models, derived from the experimental surface structure, indicate that the magnitude of the electrostatic field increases considerably in the vicinity of discontinuities. While the field near the unreconstructed perfect surface is less than 2 V/nm, it becomes larger by a factor of 2 to 4 near steps and corners. Semiempirical AMI molecular orbital calculations on models with ammonia and methane molecules adsorbed near surface defects indicate that NH and CH bond lengths increase, the corresponding bond orders decrease, compared with the gas phase. This means that the enhanced electrostatic field weakens covalent bonds, promoting dissociation. On this basis we suggest that the electrostatic field is a determining factor of the enhanced catalytic activity near surface discontinuities.

Original languageEnglish
Pages (from-to)213-218
Number of pages6
JournalJournal of Molecular Structure: THEOCHEM
Volume455
Issue number2-3
Publication statusPublished - Dec 18 1998

Fingerprint

Surface defects
surface defects
Static Electricity
Electrostatics
reactivity
Electric fields
electrostatics
electric fields
Molecular orbitals
discontinuity
molecular orbitals
Orbital calculations
Covalent bonds
Methane
covalent bonds
Bond length
Ammonia
Surface structure
catalytic activity
ammonia

Keywords

  • AMI molecular orbital method
  • Molecular electrostatic field (MEF)
  • Si(111)-(2 X 1)

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics
  • Atomic and Molecular Physics, and Optics

Cite this

Electrostatics and reactivity of surface defects on Si(111)-(2 X 1). / Kádas, Krisztina; Náray-Szabó, G.

In: Journal of Molecular Structure: THEOCHEM, Vol. 455, No. 2-3, 18.12.1998, p. 213-218.

Research output: Contribution to journalArticle

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