Unifying Microscopic and Continuum Treatments of van der Waals and Casimir Interactions.

Author: Venkataram PS1, Hermann J2, Tkatchenko A2,3, Rodriguez AW1
Affiliation: <sup>1</sup>Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA. <sup>2</sup>Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. <sup>3</sup>Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg.
Conference/Journal: Phys Rev Lett.
Date published: 2017 Jun 30
Other: Volume ID: 118 , Issue ID: 26 , Pages: 266802 , Special Notes: doi: 10.1103/PhysRevLett.118.266802. Epub 2017 Jun 29. , Word Count: 174

We present an approach for computing long-range van der Waals (vdW) interactions between complex molecular systems and arbitrarily shaped macroscopic bodies, melding atomistic treatments of electronic fluctuations based on density functional theory in the former with continuum descriptions of strongly shape-dependent electromagnetic fields in the latter, thus capturing many-body and multiple scattering effects to all orders. Such a theory is especially important when considering vdW interactions at mesoscopic scales, i.e., between molecules and structured surfaces with features on the scale of molecular sizes, in which case the finite sizes, complex shapes, and resulting nonlocal electronic excitations of molecules are strongly influenced by electromagnetic retardation and wave effects that depend crucially on the shapes of surrounding macroscopic bodies. We show that these effects together can modify vdW interaction energies and forces, as well as molecular shapes deformed by vdW interactions, by orders of magnitude compared to previous treatments based on Casimir-Polder, nonretarded, or pairwise approximations, which are valid only at macroscopically large or atomic-scale separations or in dilute insulating media, respectively.

PMID: 28707905 DOI: 10.1103/PhysRevLett.118.266802