title: Monolayer structure of tetracene on Cu (100) surface: parallel geometry.
abstract: The geometrical arrangement of tetracene on Cu (100) surface at monolayer coverage is studied by using scanning tunneling microscopy measurement and density functional theory (DFT) calculations. Tetracene molecule is found to be oriented with its molecular plane parallel to the substrate surface, and no perpendicular geometry is observed at this coverage. The molecule is aligned either in the [011] or [011] direction due to the fourfold symmetry of the Cu (100) surface. DFT calculations show that the molecule with the "flat-lying" mode has larger adsorption energy than that with the "upright standing" mode, indicating that the former is the more stable structure. With the flat-lying geometry, the carbon atoms prefer to be placed between surface Cu atoms. The molecular center prefers to be located at the bridge site between two nearest surface Cu atoms.
authors.affiliation: Physics Department, Zhejiang University, Hangzhou, 310027, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Dou
authors.forename: Jiabao
authors.initials: J
authors.lastname: Zhu
authors.forename: Qing
authors.initials: Q
authors.lastname: Liao
authors.forename: Hanjie
authors.initials: H
authors.lastname: Zhang
authors.forename: Pimo
authors.initials: P
authors.lastname: He
authors.forename: Shining
authors.initials: S
authors.lastname: Bao