ES12; The 24th Annual Workshop on Recent Developments in Electronic Structure Theory

ES12: The 24th Annual Workshop on Recent Developments in Electronic Structure Theory was held June 5-8, 2012 at Wake Forest University in Winston-Salem, NC 27109. The program consisted of 24 oral presentations, 70 posters, and 2 panel discussions. The attendance of the Workshop was comparable to or larger than previous workshops and participation was impressively diverse. The 136 participants came from all over the world and included undergraduate students, graduate students, postdoctoral researchers, and senior scientists. The general assessment of the Workshop was extremely positive in terms of the high level of scientific presentations and discussions, and in terms of the schedule, accommodations, and affordability of the meeting

Ab initio energetics and kinetics study of H2 and CH4 in the SI clathrate hydrate

We present ab initio results at the density functional theory level for the energetics and kinetics of H2 and CH4 in the SI clathrate hydrate. Our results complement a recent article by some of the authors [G.Román-Pérez et.al., Phys.Rev.Lett. 105, 145901 (2010)] in that we show additional results of the energy landscape of H2 and CH 4 in the various cages of the host material, as well as further results for energy barriers for all possible diffusion paths of H2 and CH4 through the water framework. We also report structural data of the low-pressure phase SI and the higher-pressure phases SII and S

Trapping gases in metal-organic frameworks with a selective surface molecular barrier layer

The main challenge for gas storage and separation in nanoporous materials is that many molecules of interest adsorb too weakly to be effectively retained. Instead of synthetically modifying the internal surface structure of the entire bulk—as is typically done to enhance adsorption—here we show that post exposure of a prototypical porous metal-organic framework to ethylenediamine can effectively retain a variety of weakly adsorbing molecules (for example, CO, CO₂, SO₂, C₂H₂, NO) inside the materials by forming a monolayer-thick cap at the external surface of microcrystals. Furthermore, this capping mechanism, based on hydrogen bonding as explained by ab initio modelling, opens the door for potential selectivity. For example, water molecules are shown to disrupt the hydrogen-bonded amine network and diffuse through the cap without hindrance and fully displace/release the retained small molecules out of the metal-organic framework at room temperature. These findings may provide alternative strategies for gas storage, delivery and separation