The band gap of the SnO (101) surface was estimated from the valence to conduction band energy difference in the density of states (DOS) and is ca. 1 eV. This energy gap persists after the organic molecules and water interact at the surface, further indicating a non-chemisorption interaction. Typical atomic charges, computed from the Bader partitioning scheme , for Sn in the (101) surface layer and the sub-surface layer are 2.4 and 2.3-2.4 electrons respectively. Upon interacting with all molecules, Table , the charge of the top layer Sn atoms increases to 2.5-3.6