  A calculational study of the trihalomethanes chloroform (CHCl_3) and
bromoform (CHBr_3) adsorbed on graphene is presented. The study uses the van
der Waals density functional method vdW-DF to obtain adsorption energies and
adsorption structures for these molecules of environmental concern. In this
study chloroform is found to adsorb with the H atom pointing away from
graphene, with adsorption energy 357 meV (34.4 kJ/mol). For bromoform the
calculated adsorption energy is 404 meV (39.0 kJ/mol). The corrugation of
graphene as seen by chloroform is small, the difference in adsorption energy
along the graphene plane is less than 6 meV.
