A van der Waals density functional study of adenine on graphite: Single molecular adsorption and overlayer binding

TL;DR

This study uses van der Waals density functional theory to analyze adenine molecule adsorption on graphene, determining optimal configurations, energies, and the stability of an adenine overlayer.

Contribution

It provides the first-principles calculation of adenine adsorption and overlayer cohesion on graphene using vdW-DF, highlighting differences between single-molecule and overlayer binding energies.

Findings

Adenine adsorption energy is approximately 711 meV.

The adenine overlayer exhibits significantly stronger binding than a single molecule.

Optimal binding configurations involve specific molecular orientations.

Abstract

The adsorption of an adenine molecule on graphene is studied using a first-principles van der Waals functional (vdW-DF) [Dion et al., Phys. Rev. Lett. 92, 246401 (2004)]. The cohesive energy of an ordered adenine overlayer is also estimated. For the adsorption of a single molecule, we determine the optimal binding configuration and adsorption energy by translating and rotating the molecule. The adsorption energy for a single molecule of adenine is found to be 711 meV, which is close to the calculated adsorption energy of the similar-sized naphthalene. Based on the single molecular binding configuration, we estimate the cohesive energy of a two-dimensional ordered overlayer. We find a significantly stronger binding energy for the ordered overlayer than for single-molecule adsorption.