An energy decomposition scheme is proposed for understanding of the relative low binding energy of the [4+2] cycloaddition of benzene on the Si(001)-2×1 surface. By means of density functional cluster model calculations, this scheme is demonstrated to be applicable to some other 6- and 5-member ring aromatic compounds, giving a trend that the binding energy of the [4+2] cycloaddition products of those aromatic compounds on the Si(001) surface depends strongly on their resonance energy.
The support materials of ruthenium-based catalysts for ammonia synthesis were preparedusing mixed solutions composed of magnesium nitrate, aluminum nitrate and calcium nitrate with acertain ratio. The catalysts supported on complex oxides were more active and the optimal activitytemperatures were lower than that supported on single oxide under the same conditions. Thecatalyst with Mg-Al complex oxide as support prepared by calcinating hydrotalcite-like compoundhad significantly higher activity, 38.42 mL NH3?h-1?g-1 at 673 K. The BET determination showedthat the Mg-Al complex oxide possessed large surface area, 140.95 m2?g-1, similar to γ-Al2O3.
Paired-permanent approach for VB theory is extensively developed. Canonical expansion of a paired-permanent is deduced. Furthermore, it is shown that a paired-permanent may be expressed in terms of the products of sub-paired-permanents of any given order and their corresponding minors. An ab initio spin-free valence bond program, called Xiamen, is implemented by using paired-permanent approach. Test calculation shows that Xiamen package is more efficient than some other programs based on the traditional VB algorithm, and it provides a new practical tool for quantum chemistry.
The organic modification of nano-scale TiO2 and the effect factors were studied by using dodecanoic acid and hexadecanoic acid as modifier.The results showed that the optimal modification time was 1.5h and the optimal temperature was 100℃.The surfaces of TiO2 particles were modified from hydrophilic to hydrophobic.The modification effect of hexadecanoic acid was better than that of dodecanoic acid.
