The Self-Association of Graphane Is Driven by London Dispersion and Enhanced Orbital Interactions

Wang, Changwei and Mo, Yirong and Wagner, Philipp J and Schreiner, Peter R and Jemmis, Eluvathingal D and Danovich, David and Shaik, Sason (2015) The Self-Association of Graphane Is Driven by London Dispersion and Enhanced Orbital Interactions. In: JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 11 (4). pp. 1621-1630.

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Abstract

We investigated the nature of the cohesive energy between graphane sheets via multiple CH center dot center dot center dot HC interactions, using density functional theory (DFT) including dispersion correction (Grimmes D3 approach) computations of n]graphane sigma dimers (n = 6-73). For comparison, we also evaluated the binding between graphene sheets that display prototypical pi/pi interactions. The results were analyzed using the block-localized wave function (BLW) method, which is a variant of ab initio valence bond (VB) theory. BLW interprets the intermolecular interactions in terms of frozen interaction energy (Delta E-F) composed of electrostatic and Pauli repulsion interactions, polarization (Delta E-pol), charge-transfer interaction (Delta E-CT), and dispersion effects (Delta E-disp). The BLW analysis reveals that the cohesive energy between graphane sheets is dominated by two stabilizing effects, namely intermolecular London dispersion and two-way charge transfer energy due to the sigma CH -> sigma*(HC) interactions. The shift of the electron density around the nonpolar covalent C-H bonds involved in the intermolecular interaction decreases the C-H bond lengths uniformly by 0.001 angstrom. The Delta E-CT term, which accounts for similar to 15% of the total binding energy, results in the accumulation of electron density in the interface area between two layers. This accumulated electron density thus acts as an electronic glue for the graphane layers and constitutes an important driving force in the self-association and stability of graphane under ambient conditions. Similarly, the double faced adhesive tape style of charge transfer interactions was also observed among graphene sheets in which it accounts for similar to 18% of the total binding energy. The binding energy between graphane sheets is additive and can be expressed as a sum of CH center dot center dot center dot HC interactions, or as a function of the number of C-H bonds.

Item Type:	Journal Article
Publication:	JOURNAL OF CHEMICAL THEORY AND COMPUTATION
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Keywords:	ENERGY DECOMPOSITION ANALYSIS; PI STACKING INTERACTIONS; CARBON-CARBON BONDS; INTERMOLECULAR INTERACTIONS; MOLECULAR-INTERACTIONS; THEORETICAL-ANALYSIS; STAGGERED CONFORMATION; HYDROGENATED GRAPHENE; PERTURBATION-THEORY; ROTATIONAL BARRIER
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	29 May 2015 06:33
Last Modified:	29 May 2015 06:33
URI:	http://eprints.iisc.ac.in/id/eprint/51613

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