Computational study of cycloaddition reactions on the SiC(1 0 0)-c(2 × 2) surface |
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Authors: | V M Bermudez |
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Institution: | Naval Research Laboratory, 4555 Overlook Ave., S.W., Washington, DC 20375-5347, USA |
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Abstract: | Cycloaddition reactions between 1,3-butadiene and the C-terminated SiC(1 0 0)-c(2 × 2) surface have been addressed using quantum-chemical methods. The c(2 × 2) structure consists of ---CC--- bridges between underlayer Si atoms which themselves form Si---Si bonds. Of various possible reaction products, the one formed by a 2 + 4] reaction with the ---CC--- bridge (giving a species resembling 1,4-cyclohexadiene) is the lowest in energy. Density functional calculations for the bare c(2 × 2) surface, using a cluster model with mechanical embedding, gave good agreement with structural parameters obtained in previous fully ab initio studies. Similar calculations for the cycloaddition product and for the transition state gave a reaction energy of −50.3 kcal/mol and an activation energy of +6.1 kcal/mol to form a planar ring structure lying normal to the surface. Detailed results for the frequency and infrared polarization behavior of adsorbate vibrational modes have also been obtained. |
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Keywords: | Models of surface chemical reactions Chemisorption Silicon carbide Alkenes |
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