一氧化碳在铂和铂钌表面吸附位的振动识别
Vibrational Recognition of Adsorption Sites for Carbon Monoxide on Platinum and Platinum-Ruthenium Surfaces
摘要：
本文采用Perdew-Burke-Ernzerhof广义梯度近似下的密度泛函微扰理论研究了CO在铂和铂-钌表面上的吸附振动性质。计算出的C-O伸缩频率与光谱测量结果非常吻合。当表面被钌单层覆盖时发生的频率偏移也被正确地预测。这两个位移和绝对振动频率的协议是更加显着的本地和半本地交换相关泛函预测过渡金属表面上CO的不同吸附位点的稳定性的频繁失败。我们已经调查了C-O频移引入的力和频率密度的轨道分辨分析的化学起源的状态，并评估捐赠和backdonation上的CO振动频率使用GGA +分子U的方法的效果。这些发现合理化，并建立在预测绝对振动频率的密度泛函计算的准确性，尽管在确定相对吸附能失败，在强化学吸附制度。
英文摘要：
We have studied the vibrational properties of CO adsorbed on platinum and platinum-ruthenium surfaces using density-functional perturbation theory within the Perdew-Burke-Ernzerhof generalized-gradient approximation. The calculated C-O stretching frequencies are found to be in excellent agreement with spectroscopic measurements. The frequency shifts that take place when the surface is covered with ruthenium monolayers are also correctly predicted. This agreement for both shifts and absolute vibrational frequencies is made more remarkable by the frequent failure of local and semilocal exchange-correlation functionals in predicting the stability of the different adsorption sites for CO on transition metal surfaces. We have investigated the chemical origin of the C-O frequency shifts introducing an orbital-resolved analysis of the force and frequency density of states, and assessed the effect of donation and backdonation on the CO vibrational frequency using a GGA + molecular U approach. These findings rationalize and establish the accuracy of density-functional calculations in predicting absolute vibrational frequencies, notwithstanding the failure in determining relative adsorption energies, in the strong chemisorption regime.
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