First-principles density-functional calculations were performed for the C defect on Si(001), which was experimentally identified in terms of the dissociative adsorption of a single water molecule on 2 adjacent dimers. Unlike the hitherto accepted non-magnetic structure that involved the buckling of two Si dangling bonds within the C defect, the presently proposed structure showed that the 2 dangling bonds were antiferromagnetically coupled with each other, thereby giving rise to a suppression of their buckling. This antiferromagnetic ground state of C defect reproduced the key features observed in the STM and STS experiments.

Theoretical Prediction of the Antiferromagnetic Ground State of a C Defect on Si(001). J.H.Choi, J.H.Cho: Physical Review B, 2009, 80[12], 125314