Local vibrational mechanism for negative thermal expansion: a combined neutron scattering and first-principles study

Abstract

Ask the locals: dynamic deformation of the dicopper tetracarboxylate paddlewheel unit within a metal-organic framework from square-prismatic to distorted occurs at very low energies. This deformation, which contributes strongly to the negative thermal expansion of this system, is a local vibration induced by a redistribution of electron density at the CuO junctions. © 2010, Wiley-VCH Verlag Berlin