Per Hyldgaard Research

Our research group, Materials Physics and carbon engineering, performs theoretical-physics work in the BioNano Systems Laboratory at the Department of Microtechnology and NanoScience, MC2.

RESEARCH INTERESTS

Participation in the vdW-DF program

The group participates in a long-standing Rutgers-Chalmers collaboration, the vdW-DF program on extending DFT calculations to the broad class of sparse matter by formulation of a density functional with accounts of dispersive and/or van der Waals (vdW) interactions. Together with the reserach groups of Professors Elsebeth Schröder (also at MC2), Bengt I. Lundqvist (Chalmers), and David C. Langreth (who sadly passed away in may 2011), we have worked and are working to develop, implement, test, and apply the new van der Waals density functional (vdW-DF) method.

A very large class of materials, like macro- and supra-molecular systems, have an electron distibution which, until recently have prevented accurate predictive descriptions. The class of systems are sparse materials as they contains important regions with a low or vanishing electron density where dispersive or vdW interactions contributes significantly. A predictive accounts requires quantum many-body calculations (QMBC) and efficientcy demands a formulation in terms of DFT. However, traditional state-of-the-art implementations of DFT invoke a semi-local description of the electron correlations and traditional state-of-the-art implementations fail for sparse materials where it is imperative to retain accounts of truly nonlocal correlations.

In the vdW-DF program we have been key contributors to the successfull development of a new density functional, called vdW-DF, which is fully nonlocal, which avoids double counting, and which provides simultaneous (and consistent) accounts of both dispersive or van der Waals interactions and of covalent, ionic, hydrogen and most metallic bonding. The method is proven highly efficient for molecules as well as for extended systems and provides what appears to be a first transferable (and parameter-free) account of both hard materials and sparse matter, for example, soft and supramolecular systems. The method has recieved significant international recognition.

Ab initio accounts of interacting nonequilibrium transport

The group leader has also developed a Lippmann-Schwinger collision density functional theory (LSCDFT) which provides an, in principle, exact description of nonequilibrium tunneling in the presence of full (electron-electron) interaction. While usual DFT rest on a ground-state variational property but the new theory invokes variational properties of charge transfer rates.

Revised Sep. 9, 2024 by Per Hyldgaard