title: Origin of enhanced dihydrogen-metal interaction in carboxylate bridged Cu2-paddle-wheel frameworks.
abstract: The experimentally observed enhancement of hydrogen adsorption in Cu2-tetracarboxylate paddle-wheel frameworks is investigated by ab initio density-functional theory calculations. We reveal that the puzzling enhancement is due to the effective orbital coupling between the occupied H2 σ and the unoccupied Cu 4s-derived states. The nontrivial dihydrogen-metal σ-s interaction is enabled by a strong localization of the Cu 4s orbital after hybridizing with the neighboring oxygen 2p orbitals. Based on this understanding, we predict that the dihydrogen-metal interaction can be further increased by alloying Cu with s-orbital element Zn or Mg.
authors.affiliation: Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701, Korea. yong.hyun.kim@kaist.ac.kr
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Kim
authors.forename: Joongoo
authors.initials: J
authors.lastname: Kang
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei