A van der Waals density functional study of adenine on graphene: single-molecular adsorption and overlayer binding.
ABSTRACT The adsorption of an adenine molecule on graphene is studied using a first-principles van der Waals functional, vdW-DF (Dion et al 2004 Phys. Rev. Lett. 92 246401). 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 similarly sized naphthalene. On the basis of 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.
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ABSTRACT: A density functional theory (DFT) that accounts for van der Waals (vdW) interactions in condensed matter, materials physics, chemistry, and biology is reviewed. The insights that led to the construction of the Rutgers-Chalmers van der Waals Density Functional (vdW-DF) are presented with the aim of giving a historical perspective, while also emphasising more recent efforts which have sought to improve its accuracy. In addition to technical details, we discuss a range of recent applications that illustrate the necessity of including dispersion interactions in DFT. This review highlights the value of the vdW-DF method as a general-purpose method, not only for dispersion bound systems, but also in densely packed systems where these types of interactions are traditionally thought to be negligible.Reports on Progress in Physics 12/2014; 78(6). DOI:10.1088/0034-4885/78/6/066501 · 15.63 Impact Factor
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ABSTRACT: Phenol, phenyl azide, and phenylnitrene are hazardous organic molecules; therefore, the fabrication of sensors or filters with high sorption capabilities for the chemicals is necessary. Considering van der Waals interaction, we perform first-principles density functional theory calculations to investigate the adsorption properties of the hazardous molecules on graphene. For parallel stacking configurations, AB stacking is slightly more favorable than AA stacking for all the adsorbates that we considered. We find that phenyl azide has a higher adsorption energy than phenol. Phenylnitrene forms covalent bonds with graphene in oblique stacking structures, resulting in a bandgap opening in graphene.Chemical Physics Letters 11/2014; 618. DOI:10.1016/j.cplett.2014.10.064 · 1.99 Impact Factor
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ABSTRACT: Fast and reliable DNA sequencing is a long-standing target in biomedical research. Recent advances in graphene-based electrical sensors have demonstrated their unprecedented sensitivity to adsorbed molecules, which holds great promise for label-free DNA sequencing technology. To date, the proposed sequencing approaches rely on the ability of graphene electric devices to probe molecular-specific interactions with a graphene surface. Here we experimentally demonstrate the use of graphene field-effect transistors (GFETs) as probes of the presence of a layer of individual DNA nucleobases adsorbed on the graphene surface. We show that GFETs are able to measure distinct coverage-dependent conductance signatures upon adsorption of the four different DNA nucleobases; a result that can be attributed to the formation of an interface dipole field. Comparison between experimental GFET results and synchrotron-based material analysis allowed prediction of the ultimate device sensitivity, and assessment of the feasibility of single nucleobase sensing with graphene.Nature Communications 03/2015; 6:6563. DOI:10.1038/ncomms7563 · 10.74 Impact Factor