CO Molecules on a NaCl(100) Surface: Structures, Energetics, and Vibrational Davydov Splittings at Various Coverages

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• 作者：A. Daniel Boese ; Peter Saalfrank
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：June 16, 2016
• 年：2016
• 卷：120
• 期：23
• 页码：12637-12653
• 全文大小：692K
• 年卷期：0
• ISSN：1932-7455

文摘

In this work, we study the adsorption of CO from low to high coverage at a defect-free NaCl(100) surface by means of cluster and periodic models, using highly accurate wave function-based QM:QM embedding as well as density functional theory. At low coverages, the most accurate methods predict a zero-point-corrected adsorption energy of around 13 kJ/mol, and the CO molecules are found to be oriented perpendicular to the surface. At higher coverages, lower-energy phases with nonparallel/upright, tilted orientations emerge. Besides the well-known p(2 × 1)/antiparallel phase (T/A), we find other tilted phases (tilted/irregular, T/I; tilted/spiral, T/S) as local minima. Vibrational frequencies for CO adsorbed on NaCl(100) and Davydov splittings of the C–O stretch vibration are also determined. The IR spectra are characteristic fingerprints for the relative orientation of CO molecules and may therefore be used as sensitive probes to distinguish parallel/upright from various tilted adsorption phases.