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Tuesday, March 26

On the Electron Response in van der Waals Density Functionals

Per Hyldgaard, Chalmers University of Technology, Gothenburg, Sweden
Materials Science and Technology Division Seminar
11:00 AM — 12:00 PM, Chemical and Material Sciences Building (4100),Room J-302
Contact: Valentino Cooper (coopervr@ornl.gov ), 865.574.5164

Abstract

The van der Waals density functional (vdW-DF) method [PRL 92, 246401 (2004)] for a first-principle sparse-matter theory [JPCM 21, 084203 (2009)] brings the plasmon-type response description from the local-density and generalized gradient approximations to a nonempirical, truly nonlocal correlation functional. This makes it possible to pursue systematic improvements based on physics constraints. My talk summarizes a set of Chalmers vdW-DF studies that seeks to map and analyze details in this electron-response nature. I analyze the relative importance of morphology, screening (image-plane formation), and collective effects in the vdW-DF description of molecular crystals, carbon nanotubes, and DNA dimers. Contrasting the physisorption of molecules, like benzene and C60 that presents similar interface to the substrate, provides additional insight. The corrugation for physisorption dynamics is a clear discriminator for a correct determination of the binding separation. We find that the physisorption binding energy can be used to approximate the total exchange correlation energy. Finally, we use the difference in the physisorption of such similar molecules to gauge the relative weight of the nonlocal correlation.