Adsorption characteristics of a DHTAP molecule on Cu(110)

Using density functional theory we study the adsorption of DHTAP(C18H12N4) on the Cu(110) surface. To account for long range dispersion interactions, we use the van der Waals inclusive functional (vdw-DF), optB88-vdW. We explore a total of 4 adsorption sites with the molecule’s plane parallel to the surface for 5 different coverages. We find the most energetically favorable adsorption site occurs when the center of molecule’s rings lie over the troughs present on the (110) surface, allowing the molecule’s nitrogen atoms that lack hydrogen to bond to the rows present on the (110) surface. We calculate a variety of geometrical properties of the substrate/adsorbate system including adsorption height, buckling of the first layer of the substrate, and buckling of the molecule upon adsorption on the Cu(110) surface. Along with this, we calculate several electronic properties of the system in each unit cell including change in the surface’s work function, charge transfer, and change in the width and center of the d-band of the first layer surface atoms upon the adsorption of DHTAP. Comparisons with experimental data show good agreements for adsorptions geometries.