(544dd) Benchmarks for CO and CO2 Adsorption on MnO(100): A Comparison of DFT to Experimental Data
Density functional theory (DFT) is commonly used to investigate adsorption and reaction processes on surfaces. While it is widely used, the applicability of DFT to highly correlated transition metal oxide systems with unpaired d-electrons is problematic, especially when using plane wave basis sets. A primary issue is the lack of quality experimental data for adsorbate and reaction systems on well-defined (single crystal) transition metal oxide surfaces to provide benchmarks for the applicability of current DFT methods and the future development of new methods. With this goal in mind, we have established benchmarks for the adsorption energy of CO and CO2 on MnO(100) terraces using temperature programmed desorption (TPD). In this talk we present the obtained adsorption energies of aforementioned gas molecules on MnO(100), determined using TPD experiments and compare them to DFT simulations. We find in the case of CO that the weak adsorption energy measured with TPD agrees well with DFT+U simulations that include corrections for van der Waals interactions. There is however substantial deviation between the two in the case of CO2. DFT simulations predicts that CO adsorbs at surface Mn sites in an atop configuration, while CO2 adsorbs as a bent CO2 anion at surface oxygen anion sites.