Paper AS+BI-TuA1
Vibrational Spectrum and Stability of the Long-Debated Models for the (√7×√7)R19° Phase of S/Cu(111)
Tuesday, October 30, 2012, 2:00 pm, Room 20
Recently, the structure of the copper sulfide overlayer formed on Cu(111) upon sulfur exposure has attracted attention because it serves as a substrate to form MoS2 monolayers and MoSx nanostructures in a controlled manner, which may have numerous technological applications. In the past, at least eight experimental techniques have been used to characterize the (√7×√7)R19° Cu-S overlayer on Cu(111) and to support or refute a large number of possible models but, as yet, at least three models are still in dispute. In this study, we provide firmer arguments to resolve the structure of CuS/Cu(111) at the atomic scale. Specifically, we perform density-functional-theory calculations of the total energy and the vibrational spectrum of the proposed structures to (1) attest their dynamical stability; (2) compare their thermodynamic stability as obtained from the total free energy; and (3) provide the vibrational frequencies that uniquely fingerprint these structures and which may serve for further experimental confirmation or refutation.
This work was supported in part by DOE grant DE-FG02-07ER15842
[1] Kim et al., Langmuir 27, 11650 (2011)
[2] Alfonso J. Phys. Chem. C 115, 17077 (2011)