Screening of core holes in isolated and chemisorbed carbon monoxide

The process of core-hole screening in the carbon monoxide molecule is explained from the single-particle perspective of Xα local density functional theory. A cluster model is employed to compare free and chemisorbed CO. It is found that the π electrons provide the major component of the screening charge. By the consideration of the extramolecular screening as the difference between the screening in Cuₙ CO clusters and isolated CO, a direct comparison can be made with the single-screening-orbital concept proposed by Lang and Williams.