Optical van-der-Waals forces in molecules: from electronic Bethe-Salpeter calculations to the many-body dispersion model

Abstract

Molecular forces induced by optical excitations are connected to a wide range of phenomena, from chemical bond dissociation to intricate biological processes that underpin vision. Commonly, the description of optical excitations requires the solution of computationally demanding electronic Bethe-Salpeter equation (BSE). However, when studying non-covalent interactions in large-scale systems, more efficient methods are desirable. Here we introduce an effective approach based on coupled quantum Drude oscillators (cQDO) as represented by the many-body dispersion model. We find that the cQDO Hamiltonian yields semi-quantitative agreement with BSE calculations and that both attractive and repulsive optical van der Waals (vdW) forces can be induced by light. These optical-vdW interactions dominate over vdW dispersion in the long-distance regime, showing a complexity that grows with system size. Evidence of highly non-local forces in the human formaldehyde dehydrogenase 1MC5 protein suggests the ability to selectively activate collective molecular vibrations by photoabsorption, in agreement with recent experiments.

Quantum-Mechanically Enhanced Water Flow in Subnanometer Carbon Nanotubes

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Photobiomodulation in Alzheimer’s Disease—A Complementary Method to State-of-the-Art Pharmaceutical Formulations and Nanomedicine?

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Optimized Quantum Drude Oscillators for Atomic and Molecular Response Properties

“…The quantum Drude oscillator (QDO) is arguably the most powerful Hamiltonian (see the Supporting Information) for accurate and efficient modeling of atomic and molecular response. ,− Within the coarse-grained QDO model, the response of valence electrons is described via a quasi-particle drudon with a negative charge − q and mass μ, harmonically bound to a positively charged pseudonucleus of charge q with a characteristic frequency ω. The many-body extension of the QDO model (the coupled QDO model) has been widely employed to study both molecules and materials, including their electronic , and optical properties, polarization, , dispersion, ,,− and exchange − interactions, as well as a wealth of nonadditive field effects in quantum mechanics , and quantum electrodynamics. , Coupled QDOs are also extensively used in the development of van der Waals (vdW) density functionals, ,, quantum mechanical , and polarizable force fields, − as well as recent machine learning force fields. , Despite such a wide applicability of the coupled QDO model, its success in describing real atoms remains fundamentally unexplained, and the optimal mapping between atoms and oscillators has not been established. In this Letter, we develop an optimized parametrization (OQDO) in which the parameters are fixed by using only the well-known atomic dipolar properties.…”