TY - JOUR
T1 - Origin of nonlocal interactions in adsorption of polar molecules on Si (001) -2×1
AU - Wang, Yun
AU - Hwang, Gyeong S.
N1 - Funding Information:
The authors acknowledge the Welch Foundation (Grant No. F-1535) for their financial support of this work. All their calculations were performed using supercomputers at the Texas Advanced Computing Center at the University of Texas at Austin.
PY - 2005/4/22
Y1 - 2005/4/22
N2 - Using density functional theory slab calculations, we have investigated (i) the origin of nonlocal interactions occurring in the adsorption of small polar molecules (H2 O,N H3, C H3 OH,C H3 N H2) on the clean Si (001) -2×1 surface and (ii) the nonlocal effects on two-dimensional arrangement of adsorbates. Our results show the adsorption properties are significantly altered in the presence of adsorbates on an adjacent dimer along a row. We have identified that the coverage dependent behavior arises from a combination of (i) surface polarization change, (ii) adsorbate-induced charge delocalization, (iii) adsorbate-adsorbate repulsion, and (iv) hydrogen bonding. The nucleophilic-electrophilic molecular adsorption involves charge delocalization to neighboring dimers along a row, which in turn undermines molecular adsorption on the neighboring dimers. Nonlocal effects associated with polar interactions with neighboring dimers and adsorbates vary with adsorption system. While such polar interactions are unimportant in C H3 OH adsorption, hydrogen bonding and adsorbate-adsorbate repulsion play an important role in determining the adsorption structures of H2 O and N H3 C H3 N H2, respectively. In addition, the electrostatic attraction with the buckled-up Si atoms of adjacent dimers contributes to stabilization of H2 O, N H3, and C H3 N H2 adsorption. We also discuss kinetic effects on two-dimensional ordering of adsorbates, in conjunction with surface phase transition and adsorption-dissociation rates.
AB - Using density functional theory slab calculations, we have investigated (i) the origin of nonlocal interactions occurring in the adsorption of small polar molecules (H2 O,N H3, C H3 OH,C H3 N H2) on the clean Si (001) -2×1 surface and (ii) the nonlocal effects on two-dimensional arrangement of adsorbates. Our results show the adsorption properties are significantly altered in the presence of adsorbates on an adjacent dimer along a row. We have identified that the coverage dependent behavior arises from a combination of (i) surface polarization change, (ii) adsorbate-induced charge delocalization, (iii) adsorbate-adsorbate repulsion, and (iv) hydrogen bonding. The nucleophilic-electrophilic molecular adsorption involves charge delocalization to neighboring dimers along a row, which in turn undermines molecular adsorption on the neighboring dimers. Nonlocal effects associated with polar interactions with neighboring dimers and adsorbates vary with adsorption system. While such polar interactions are unimportant in C H3 OH adsorption, hydrogen bonding and adsorbate-adsorbate repulsion play an important role in determining the adsorption structures of H2 O and N H3 C H3 N H2, respectively. In addition, the electrostatic attraction with the buckled-up Si atoms of adjacent dimers contributes to stabilization of H2 O, N H3, and C H3 N H2 adsorption. We also discuss kinetic effects on two-dimensional ordering of adsorbates, in conjunction with surface phase transition and adsorption-dissociation rates.
UR - http://www.scopus.com/inward/record.url?scp=21244501786&partnerID=8YFLogxK
U2 - 10.1063/1.1884596
DO - 10.1063/1.1884596
M3 - Article
AN - SCOPUS:21244501786
SN - 0021-9606
VL - 122
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 16
M1 - 164706
ER -