Multiconfigurational self-consistent field study of the silicon carbide (001) surface

Abstract

Multiconfigurational self-consistent field calculations have been performed to investigate structural and electronic properties of cubic siliconcarbide (001) (SiC (001)) surfaces. The dimer on silicon-terminated SiC (001) (Si-SiC (001)) is found to be diradical in nature, due to destabilization of the π bond by bending the dimer. Since the SiClattice constant is larger than that of diamond, the >C=C< dimer on the carbonterminated SiC (001) (C-SiC (001)) surface is flatter and its π bond is stronger than those on diamond (001). The bridging dimer on the C-SiC (001) exhibits relatively small multiconfigurational character despite its bent geometry. H2adsorption onto the Si-SiC (001) diradical dimer is more favorable than that onto the partial π bonded Si (001) dimer. As the dimer geometry becomes flatter, the π bond becomes stronger and the H2adsorption on the dimer becomes less favorable. Multiconfigurational self-consistent field calculations have been performed to investigate structural and electronic properties of cubic silicon carbide ͑001͒ ͑SiC ͑001͒͒ surfaces. The dimer on silicon-terminated SiC ͑001͒ ͑Si-SiC ͑001͒͒ is found to be diradical in nature, due to destabilization of the bond by bending the dimer. Since the SiC lattice constant is larger than that of diamond, the ϾCvCϽ dimer on the carbon-terminated SiC ͑001͒ ͑C-SiC ͑001͒͒ surface is flatter and its bond is stronger than those on diamond ͑001͒. The bridging dimer on the C-SiC ͑001͒ exhibits relatively small multiconfigurational character despite its bent geometry. H 2 adsorption onto the Si-SiC ͑001͒ diradical dimer is more favorable than that onto the partial bonded Si ͑001͒ dimer. As the dimer geometry becomes flatter, the bond becomes stronger and the H 2 adsorption on the dimer becomes less favorable.

CASSCF and MRMP2 investigation of the interaction of arsenic adatoms with carbon dimers on the diamond (100)-2 × 1 surface

“…For performing QM/MM calculations, the SIMOMM (Surface Integrated Molecular Orbital/Molecular Mechanics) method [34] was used. This method was successfully applied to the study of different adsorbates on Si(100) [25,35,36], SiC(100) [37], and diamond (100) [19] surfaces. In the present work, it was employed to characterize the larger model system described in Section 2.1, C 292 H 120.…”

Creation of Ordered Layers on Semiconductor Surfaces: An ab Initio Molecular Dynamics Study of the SiC(001)-3×2 and SiC(100)-c(2×2) Surfaces

“…An important consideration in cycloaddition reactions such as those studied here is the possibility of their occurring through a radical mechanism. Multi-reference self consistent field cluster calculations of the SiC(001)-2x1 surface suggest that the topmost dimer exhibits significant diradical character (Tamura & Gordon, 2003), and since DFT is a single-reference method, multi-reference contributions are generally not included.…”

Semiconductor color-center structure and excitation spectra: Equation-of-motion coupled-cluster description of vacancy and transition-metal defect photoluminescence

“…The SIMOMM framework imposes a less rigid treatment of the capping atoms than its predecessor, the IMOMM model of Maseras and Morokuma [41], and this reduces artificial strain imposed on the QM structure. SIMOMM was originally developed for the study of surface chemical systems, and by now its utility has been demonstrated repeatedly for describing chemistry on Si and SiC surfaces [42][43][44][45][46][47][48][49][50][51]. SIMOMM geometry optimizations are perfomed under the Born-Oppenheimer approximation, which in this case is based on extremely robust assumptions [52].…”