Chemisorption of Guanine on Cu(110)

We use density functional theory (PBE) to calculate the adsorption of a guanine molecule on Cu(110). At saturation coverage, guanine adsorbs tilted with the oxygen atom strongly bound to one of the surface atoms at a height of 2.12 {\AA} above this surface atom with a binding energy of 430 meV/molecule. The substrate top layer atoms show a buckling of 0.22 {\AA} , while the molecule experiences a twist from the flat configuration in the gas phase. The dz$^{2}$ state of the copper atom -that is bound to the oxygen atom- presents an enhancement in its density near the Fermi level. We calculated a drop in the work function of 0.34 eV upon adsorption of guanine on Cu(110). These effects classify this system as chemisorption.