### Abstract

We presented a detailed quantum dynamics study for dissociative adsorption of H_{2} at different sites of Cu(111) surface to investigate the effect of surface corrugation and site specificity. The theoretical study employed a four-dimensional (4-D) "fixed-site" model, in which the lateral coordinates (X,Y) of the center of mass of the diatom are fixed at the impact site, but the remaining four degrees of freedom are explicitly treated in quantum calculations. The inclusion of the azimuthal angle ø in the present 4-D model is a significant step forward in theoretical studies beyond the 3-D "flat surface" model. This 4-D "fixed-site" model allows us to investigate explicitly the local corrugation effect that was not possible using the 3-D flat-surface model. We incorporated the latest ab initio data of Hammer et al. in constructing the LEPS potential energy surface, which gives the lowest dissociation barrier over the bridge site. 4-D dynamics calculations are performed in the present study to mimic a normal incidence of H_{2} at three symmetric sites on Cu(111): bridge, atop, and center sites with the corresponding rotation symmetries. Our results show that a hydrogen impact at a high symmetry site (six-fold atop site) shows little corrugation effect while impact at low symmetry site (two-fold bridge site) shows a large corrugation effect. In particular, our calculation shows that the inclusion of surface corrugation preserves the strong rotational orientation effect observed in flat-surface model calculations. The effect of homonuclear symmetry persists at high symmetry atop site, and to a lesser degree at a low symmetry bridge site. The contour plot of the wavefunction in the current 4-D model shows explicitly that hydrogen atoms following the dissociation of H _{2} over the bridge site do not settle at the neighboring center site, but migrate to the next available center site. Our study demonstrated that the 4-D fixed-site model is very useful in investigating surface corrugation and molecule site specificity in model-surface reactions.

Original language | English (US) |
---|---|

Pages (from-to) | 6280-6289 |

Number of pages | 10 |

Journal | The Journal of chemical physics |

Volume | 102 |

Issue number | 15 |

State | Published - 1995 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

**Quantum adsorption dynamics of a diatomic molecule on surface : Four-dimensional fixed-site model for H2 on Cu(111).** / Dai, Jiqiong; Zhang, John.

Research output: Contribution to journal › Article

*The Journal of chemical physics*, vol. 102, no. 15, pp. 6280-6289.

}

TY - JOUR

T1 - Quantum adsorption dynamics of a diatomic molecule on surface

T2 - Four-dimensional fixed-site model for H2 on Cu(111)

AU - Dai, Jiqiong

AU - Zhang, John

PY - 1995

Y1 - 1995

N2 - We presented a detailed quantum dynamics study for dissociative adsorption of H2 at different sites of Cu(111) surface to investigate the effect of surface corrugation and site specificity. The theoretical study employed a four-dimensional (4-D) "fixed-site" model, in which the lateral coordinates (X,Y) of the center of mass of the diatom are fixed at the impact site, but the remaining four degrees of freedom are explicitly treated in quantum calculations. The inclusion of the azimuthal angle ø in the present 4-D model is a significant step forward in theoretical studies beyond the 3-D "flat surface" model. This 4-D "fixed-site" model allows us to investigate explicitly the local corrugation effect that was not possible using the 3-D flat-surface model. We incorporated the latest ab initio data of Hammer et al. in constructing the LEPS potential energy surface, which gives the lowest dissociation barrier over the bridge site. 4-D dynamics calculations are performed in the present study to mimic a normal incidence of H2 at three symmetric sites on Cu(111): bridge, atop, and center sites with the corresponding rotation symmetries. Our results show that a hydrogen impact at a high symmetry site (six-fold atop site) shows little corrugation effect while impact at low symmetry site (two-fold bridge site) shows a large corrugation effect. In particular, our calculation shows that the inclusion of surface corrugation preserves the strong rotational orientation effect observed in flat-surface model calculations. The effect of homonuclear symmetry persists at high symmetry atop site, and to a lesser degree at a low symmetry bridge site. The contour plot of the wavefunction in the current 4-D model shows explicitly that hydrogen atoms following the dissociation of H 2 over the bridge site do not settle at the neighboring center site, but migrate to the next available center site. Our study demonstrated that the 4-D fixed-site model is very useful in investigating surface corrugation and molecule site specificity in model-surface reactions.

AB - We presented a detailed quantum dynamics study for dissociative adsorption of H2 at different sites of Cu(111) surface to investigate the effect of surface corrugation and site specificity. The theoretical study employed a four-dimensional (4-D) "fixed-site" model, in which the lateral coordinates (X,Y) of the center of mass of the diatom are fixed at the impact site, but the remaining four degrees of freedom are explicitly treated in quantum calculations. The inclusion of the azimuthal angle ø in the present 4-D model is a significant step forward in theoretical studies beyond the 3-D "flat surface" model. This 4-D "fixed-site" model allows us to investigate explicitly the local corrugation effect that was not possible using the 3-D flat-surface model. We incorporated the latest ab initio data of Hammer et al. in constructing the LEPS potential energy surface, which gives the lowest dissociation barrier over the bridge site. 4-D dynamics calculations are performed in the present study to mimic a normal incidence of H2 at three symmetric sites on Cu(111): bridge, atop, and center sites with the corresponding rotation symmetries. Our results show that a hydrogen impact at a high symmetry site (six-fold atop site) shows little corrugation effect while impact at low symmetry site (two-fold bridge site) shows a large corrugation effect. In particular, our calculation shows that the inclusion of surface corrugation preserves the strong rotational orientation effect observed in flat-surface model calculations. The effect of homonuclear symmetry persists at high symmetry atop site, and to a lesser degree at a low symmetry bridge site. The contour plot of the wavefunction in the current 4-D model shows explicitly that hydrogen atoms following the dissociation of H 2 over the bridge site do not settle at the neighboring center site, but migrate to the next available center site. Our study demonstrated that the 4-D fixed-site model is very useful in investigating surface corrugation and molecule site specificity in model-surface reactions.

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M3 - Article

VL - 102

SP - 6280

EP - 6289

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 15

ER -