Alexandre Tkatchenko Fritz Haber Institute of the Max Planck Society

Collective van der Waals Interactions and their Relevance in Biology, Chemistry, and Physics

2-3:00pm in Pfizer Auditorium

Van der Waals (vdW) interactions are ubiquitous in nature,
playing a major role in defining the structure, stability,
and function for a wide variety of molecules and materials.
Thus, reliable description of vdW interactions is essential
for improving our understanding of a multitude of systems
in biology, chemistry, and condensed matter physics.

It is widely recognized that vdW interactions arise from
collective electronic fluctuations and their accurate description
requires the usage of quantum electrodynamics. Despite this well-known fact,
most of the widely employed atomistic models for vdW interactions are still
based on a simple pairwise interacting "atoms-in-molecules" picture, ignoring
the rather strong collective effects.

To address this problem, we have recently developed an efficient method,
based on coupled atomic response functions, to accurately compute the
long-range non-additive many-body vdW energy in molecules and materials [1].
We demonstrate that collective many-body effects play a significant role
even for rather small molecules, becoming crucial for an accurate treatment
of larger, more complex, systems. Our method achieves accuracy close to that
of the "gold standard" of quantum chemistry, namely CCSD(T). However, the
computational cost of our method is negligible compared to the underlying
DFT calculation, enabling calculations for thousands of atoms.

Applications to be discussed include (hard and soft) bulk materials [2,3],
organic/organic and organic/inorganic interfaces [4], the structure
and dynamics of peptides and DNA [5,6], and vdW scaling laws in
nanostructured materials [7]. In all cases it is found that vdW interactions
play a noticeable, if not crucial role, not just for quantitative values but
also for the qualitative behavior.

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[1] A. Tkatchenko, R. A. DiStasio Jr., R. Car, and M. Scheffler, Phys. Rev. Lett. 108, 236402 (2012).
[2] G. Zhang, A. Tkatchenko, J. Paier, H. Appel, and M. Scheffler, Phys. Rev. Lett. 107, 245501 (2011).
[3] A. M. Reilly and A. Tkatchenko, J. Phys. Chem. Lett. 4, 1028 (2013).
[4] V. G. Ruiz, W. Liu, E. Zojer, M. Scheffler, and A. Tkatchenko, Phys. Rev. Lett. 108, 146103 (2012).
[5] A. Tkatchenko, M. Rossi, V. Blum, J. Ireta, and M. Scheffler, Phys. Rev. Lett. 106, 118102 (2011).
[6] R. A. DiStasio Jr., O. A. von Lilienfeld, and A. Tkatchenko, PNAS 109, 14791 (2012).
[7] V. V. Gobre and A. Tkatchenko, Nature Communications 4:2341 (2013).