Fundamental Aspects of Van der Waals Interactions in Physics and Chemistry. – (Peter Szabo / LCPQ / Seminar). – 17/ 09 /2026, 14H

Séminaire du LCPQ

Peter Szabo KU Leuven

Seminar LCPQ, 15/09/2026, 14H

Summary :
Van der Waals (vdW) interactions arise from electronic zero-point and thermal fluctuations, scaling rapidly with system size. Despite being weak compared to covalent and ionic bonds, they are fundamental in determining the structure, stability, and spectroscopic properties of molecules and materials. These interactions can be described through linear response functions, which provide a quantitative framework for understanding and predicting how systems react to small perturbations. Among them polarizability is the most significant, governing intermolecular interactions and determining spectroscopic observables. Accurate modeling of polarizability is also crucial in developing new methods in density functional theory, where capturing nonlocal vdW effects remains a major challenge.
In our recent study [1], we explored the system-size dependence of polarizability, denoted as α, within a quantum-mechanical framework. Interestingly, we found that the general quantum-mechanical system-size dependence of polarizability follows a four-dimensional scaling law, which deviates from the commonly accepted classical textbook result (classical 3D scaling: α ~ Volume ~ R3, where R represents the system’s radius). This four-dimensional scaling law is a pure quantum effect arising from quantum fluctuations and remains valid for quantum-mechanical systems with varying spatial dimensions, symmetry, and excitation states. Furthermore, it is also applicable to many-particle systems, as shown by accurately predicting the dipole polarizability of atoms and small organic molecules. Our unified formula can be extended to arbitrary response functions by renormalizing the quantum fluctuations caused by external perturbations.

References:

[1] P. Szabo, et al., Phys. Rev. Lett. 128, 070602, 2022