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Modifying molecular interactions by squeezing molecules

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Published on Monday, 11 January 2021

In a paper published in Nature Communications on 08 January 2021, the Theoretical Chemical Physics group, from the Department of Physics and Materials Science (DPhyMS) at the University of Luxembourg, developed a practically applicable method that is able to accurately describe interactions between molecules in an arbitrary confining environment or ”squeezed molecules”.

Most molecular materials and biological systems consist of molecules interacting among themselves and with their environment. For molecules in vacuum and simple crystalline materials, intermolecular interactions are well understood and explored already since decades. However, in real biological and chemical systems, molecules tread into nanoscale voids and interact within confined spaces, where new phenomena arise. A prominent example of such behavior is the flow rate of water through carbon nanotubes, which increases with decreasing radius of the nanotube, a fact that has been puzzling scientists ever since its observation in 2016 [Nature 537, 210 (2016)].

Dr. Martin Stöhr, Prof. Dr. Alexandre Tkatchenko, and collaborators from the Department of Physics and Materials Science (DPhyMS), wrote a paper, which has now been published in Nature Communications, highlighting the development of an applicable method that is able to describe interactions between molecules in an arbitrary confining environment or ”squeezed molecules”. One such interaction, known as dispersion-polarization, arises from the change in the average distribution of the electronic charge density due to quantum fluctuations.

Using their new efficient method, the researchers have been able to show that such so-far neglected effects in fact lead to considerable modifications of molecular interactions in realistic complex systems. For example, when squeezing molecules into carbon nanotubes, the dispersion-polarization effect surprisingly gives rise to a purely repulsive net interaction. Such ”molecular squeezing” could ultimately lead to a reduction of the microscopic viscosity of water and explain the increased flow rate through carbon nanotubes as well as a variety of other recent puzzling experimental observations.

”Nanoscale confinement is an ubiquitous setting for nanotechnological applications and biomolecular systems. Identifying qualitative changes to intermolecular interactions can be a stepping stone for the advancement of such technologies and our understanding of realistic and practically-relevant systems”, explains Dr. Martin Stöhr, Research and development specialist at DPhyMS, and the first author of the study.

”I am proud of our group’s work that combines interdisciplinary expertise in physics, chemistry, and biology and shows that fundamental physical mechanisms often turn out to be key for the understanding of novel properties and functionality of molecules and materials in the real world”, concludes Alexandre Tkatchenko, Professor of Theoretical Chemical Physics (DPhyMS) at the University, and the corresponding author of the study.

Link to the paper in Nature Communications: https://www.nature.com/articles/s41467-020-20473-w