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Title: An ab initio cluster study of the structure of the Si(001) surface

Abstract

Ab initio calculations, employing double zeta plus polarization (DZP) basis sets and generalized valence bond (GVB) wave functions, have been performed on clusters of varying size, to investigate the utility of such clusters as prototypes for the study of silicon surfaces, and to investigate the effect of the level of theory used on predicted results. This work builds on landmark papers by Goddard in 1982 and Paulus in 1998 that demonstrate that a single reference wave function description of the silicon dimer bond is incorrect, and that a multireference description results in a symmetric dimer in a silicon cluster containing one dimer. In this work, it is shown that the imposition of arbitrary geometrical constraints (fixing subsurface atoms at lattice positions) on cluster models of the Si(100) surface can also lead to nonphysical results. Calculations on the largest clusters, without geometrical constraints, reveal that surface rearrangement due to dimer bond formation is ''felt'' several layers into the bulk. The predicted subsurface displacements compare favorably to experiment. Thus, small clusters, such as Si{sub 9}H{sub 12}, cannot adequately represent bulk behavior. Vibrational analysis shows that dimer buckling modes require minimal excitation energy, so the experimental observation of buckled dimers on silicon surfacesmore » may reflect the ease with which a symmetric dimer can be perturbed from its minimum energy structure. In the study of surface reconstruction and relaxation, and the associated issue of the buckling of dimer surfaces, it is critical to use adequate wave functions. As shown in this work and previously by Goddard and Paulus, this generally means that multireference treatments are needed to correctly treat the dangling bonds. (c) 2000 American Institute of Physics.« less

Authors:
 [1];  [1];  [2]
  1. Department of Engineering Physics, Air Force Institute of Technology, Dayton, Ohio 45433 (United States)
  2. Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
Publication Date:
OSTI Identifier:
20215290
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 6; Other Information: PBD: 8 Feb 2000; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SILICON; SURFACES; STRUCTURE FACTORS; SOLID CLUSTERS; SIZE; CHEMICAL BONDS; THEORETICAL DATA

Citation Formats

Shoemaker, James, Burggraf, Larry W, and Gordon, Mark S. An ab initio cluster study of the structure of the Si(001) surface. United States: N. p., 2000. Web. doi:10.1063/1.480930.
Shoemaker, James, Burggraf, Larry W, & Gordon, Mark S. An ab initio cluster study of the structure of the Si(001) surface. United States. doi:10.1063/1.480930.
Shoemaker, James, Burggraf, Larry W, and Gordon, Mark S. Tue . "An ab initio cluster study of the structure of the Si(001) surface". United States. doi:10.1063/1.480930.
@article{osti_20215290,
title = {An ab initio cluster study of the structure of the Si(001) surface},
author = {Shoemaker, James and Burggraf, Larry W and Gordon, Mark S},
abstractNote = {Ab initio calculations, employing double zeta plus polarization (DZP) basis sets and generalized valence bond (GVB) wave functions, have been performed on clusters of varying size, to investigate the utility of such clusters as prototypes for the study of silicon surfaces, and to investigate the effect of the level of theory used on predicted results. This work builds on landmark papers by Goddard in 1982 and Paulus in 1998 that demonstrate that a single reference wave function description of the silicon dimer bond is incorrect, and that a multireference description results in a symmetric dimer in a silicon cluster containing one dimer. In this work, it is shown that the imposition of arbitrary geometrical constraints (fixing subsurface atoms at lattice positions) on cluster models of the Si(100) surface can also lead to nonphysical results. Calculations on the largest clusters, without geometrical constraints, reveal that surface rearrangement due to dimer bond formation is ''felt'' several layers into the bulk. The predicted subsurface displacements compare favorably to experiment. Thus, small clusters, such as Si{sub 9}H{sub 12}, cannot adequately represent bulk behavior. Vibrational analysis shows that dimer buckling modes require minimal excitation energy, so the experimental observation of buckled dimers on silicon surfaces may reflect the ease with which a symmetric dimer can be perturbed from its minimum energy structure. In the study of surface reconstruction and relaxation, and the associated issue of the buckling of dimer surfaces, it is critical to use adequate wave functions. As shown in this work and previously by Goddard and Paulus, this generally means that multireference treatments are needed to correctly treat the dangling bonds. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.480930},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 6,
volume = 112,
place = {United States},
year = {2000},
month = {2}
}