Goumans T P M, Wander Adrian, Brown Wendy A, Catlow C Richard A
Chemistry Department, University College London, 20 Gordon Street, London, UK WC1H 0AJ.
Phys Chem Chem Phys. 2007 May 7;9(17):2146-52. doi: 10.1039/b701176h. Epub 2007 Feb 23.
The structure and surface energies of the cleaved, reconstructed, and fully hydroxylated (001) alpha-quartz surface of various thicknesses are investigated with periodic density functional theory (DFT). The properties of the cleaved and hydroxylated surface are reproduced with a slab thickness of 18 atomic layers, while a thicker 27-layer slab is necessary for the reconstructed surface. The performance of the hybrid DFT functional B3LYP, using an atomic basis set, is compared with the generalised gradient approximation, PBE, employing plane waves. Both methodologies give similar structures and surface energies for the cleaved and reconstructed surfaces, which validates studying these surfaces with hybrid DFT. However, there is a slight difference between the PBE and B3LYP approach for the geometry of the hydrogen bonded network on the hydroxylated surface. The PBE adsorption energy of CO on a surface silanol site is in good agreement with experimental values, suggesting that this method is more accurate for hydrogen bonded structures than B3LYP. New hybrid functionals, however, yield improved weak interactions. Since these functionals also give superior activation energies, we recommend applying the new functionals to contemporary issues involving the silica surface and adsorbates on this surface.
利用周期性密度泛函理论（DFT）研究了不同厚度的解理、重构和完全羟基化的（001）α-石英表面的结构和表面能。对于解理和羟基化表面，当平板厚度为18个原子层时可再现其性质，而对于重构表面则需要更厚的27层平板。使用原子基组的混合DFT泛函B3LYP的性能与采用平面波的广义梯度近似PBE进行了比较。两种方法对于解理和重构表面给出了相似的结构和表面能，这验证了使用混合DFT研究这些表面的合理性。然而，对于羟基化表面上氢键网络的几何结构，PBE和B3LYP方法之间存在细微差异。CO在表面硅醇位点上的PBE吸附能与实验值吻合良好，表明该方法对于氢键结构比B3LYP更准确。然而，新的混合泛函产生了改进的弱相互作用。由于这些泛函还给出了更好的活化能，我们建议将新泛函应用于涉及二氧化硅表面及该表面上吸附质的当代问题。
