Halogen bonds, characterized by directionality, tunability,
hydrophobicity,
and variable sizes, are ideal noncovalent interactions to design and
control the formation of self-assembled nanostructures. The specific
self-assembly cases formed by the halogen-bonding interaction have
been well studied by scanning tunneling microscopy (STM) experiments
and density functional theory (DFT) calculations. However, there is
a lack of systematic theoretical adsorption studies on halogenated
molecules. In this work, the adsorption of halobenzenes and 1,3,5-trihalobenzenes
on the Cu(111) surface was examined by dispersion-corrected DFT methods.
The adsorption geometries, noncovalent molecule–surface interactions,
electronic densities, and electrostatic potential maps were examined
for their most stable adsorption sites using the DFT-D4 method. Our
calculations revealed that the iodo compounds favor a different adsorption
geometry from aryl chlorides and bromides. Down the halogen group
(Cl to I), the adsorption energy increases and the distance between
the halogen atom and Cu surface decreases, which indicates stronger
molecule–surface interactions. This is supported by the changes
in the density of states upon adsorption. Noncovalent interaction
analysis was also employed to further understand the nature and relative
strength of the molecule–surface interactions. Electrostatic
potential maps revealed that the positive character of the halogen
sigma hole becomes stronger upon adsorption. Thus, surface adsorption
of the halogenated molecule will enhance the formation of intermolecular
halogen bonds. The present theoretical findings are expected to contribute
toward a more comprehensive understanding of halogen bonding on the
Cu(111) surface.