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Comprehensive Quantum Framework for Describing Retarded and Non-Retarded Molecular Interactions in External Electric Fields
TL;DR: In this article, the impact of electric fields on both non-retarded and retarded noncovalent interactions between atoms or molecules is investigated. And the interplay between these three types of interactions enables the manipulation of molecular dimer conformations by applying transversal or longitudinal electric fields along the intermolecular axis.
Abstract: We employ various quantum-mechanical approaches for studying the impact of electric fields on both nonretarded and retarded noncovalent interactions between atoms or molecules. To this end, we apply perturbative and non-perturbative methods within the frameworks of quantum mechanics (QM) as well as quantum electrodynamics (QED). In addition, to provide a transparent physical picture of the different types of resulting interactions, we employ a stochastic electrodynamic approach based on the zero-point fluctuating field. Atomic response properties are described via harmonic Drude oscillators - an efficient model system that permits an analytical solution and has been convincingly shown to yield accurate results when modeling non-retarded intermolecular interactions. The obtained intermolecular energy contributions are classified as field-induced (FI) electrostatics, FI polarization, and dispersion interactions. The interplay between these three types of interactions enables the manipulation of molecular dimer conformations by applying transversal or longitudinal electric fields along the intermolecular axis. Our framework combining four complementary theoretical approaches paves the way toward a systematic description and improved understanding of molecular interactions when molecules are subject to both external and vacuum fields.
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Journal Article•
TL;DR: In this paper, the subject of quantum electrodynamics is presented in a new form, which may be dealt with in two ways: using redundant variables and using a direct physical interpretation.
Abstract: THE subject of quantum electrodynamics is extremely difficult, even for the case of a single electron. The usual method of solving the corresponding wave equation leads to divergent integrals. To avoid these, Prof. P. A. M. Dirac* uses the method of redundant variables. This does not abolish the difficulty, but presents it in a new form, which may be dealt with in two ways. The first of these needs only comparatively simple mathematics and is directly connected with an elegant general scheme, but unfortunately its wave functions apply only to a hypothetical world and so its physical interpretation is indirect. The second way has the advantage of a direct physical interpretation, but the mathematics is so complicated that it has not yet been solved even for what appears to be the simplest possible case. Both methods seem worth further study, failing the discovery of a third which would combine the advantages of both.
1,398 citations
TL;DR: It is demonstrated that electron-photon correlation is fundamental to describe intermolecular interactions in strong light-matter coupling and proposed optical cavities as a novel tool to manipulate and control ground state properties, solvent effects, and intermolescular interactions for molecules and materials.
Abstract: Intermolecular bonds are weak compared to covalent bonds, but they are strong enough to influence the properties of large molecular systems. In this work, we investigate how strong light-matter coupling inside an optical cavity can modify these intermolecular forces. We perform a detailed comparison between currently available ab initio electron-photon methodologies. The electromagnetic field inside the cavity can modulate the ground state properties of weakly bound complexes. Controlling the field polarization, the interactions can be stabilized or destabilized, and electron densities, dipole moments, and polarizabilities can be altered. We demonstrate that electron-photon correlation is fundamental to describe intermolecular interactions in strong light-matter coupling. This work proposes optical cavities as a novel tool to manipulate and control ground state properties, solvent effects, and intermolecular interactions for molecules and materials.
47 citations
Journal Article•
TL;DR: It is demonstrated that the long-range interaction between spatially confined vdW dimers becomes repulsive when accounting for the full Coulomb interaction between charge fluctuations.
Abstract: It is an undisputed textbook fact that nonretarded van der Waals (vdW) interactions between isotropic dimers are attractive, regardless of the polarizability of the interacting systems or spatial dimensionality. The universality of vdW attraction is attributed to the dipolar coupling between fluctuating electron charge densities. Here, we demonstrate that the long-range interaction between spatially confined vdW dimers becomes repulsive when accounting for the full Coulomb interaction between charge fluctuations. Our analytic results are obtained by using the Coulomb potential as a perturbation over dipole-correlated states for two quantum harmonic oscillators embedded in spaces with reduced dimensionality; however, the long-range repulsion is expected to be a general phenomenon for spatially confined quantum systems. We suggest optical experiments to test our predictions, analyze their relevance in the context of intermolecular interactions in nanoscale environments, and rationalize the recent observation of anomalously strong screening of the lateral vdW interactions between aromatic hydrocarbons adsorbed on metal surfaces.
4 citations
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TL;DR: In this paper, the interaction between two neutral atoms or molecules subject to a uniform static electric field, using quantum mechanics (QM) and quantum electrodynamics (QED) applied to coupled harmonic Drude oscillators, is studied.
Abstract: We study the interaction between two neutral atoms or molecules subject to a uniform static electric field, using quantum mechanics (QM) and quantum electrodynamics (QED) applied to coupled harmonic Drude oscillators. Our focus is to understand the interplay between dispersion interactions and field-induced electrostatics and polarization in both retarded and non-retarded regimes. We present an exact solution for two coupled oscillators using QM and Rayleigh-Schr\"odinger perturbation theory, demonstrating that the external field controls the strength of different intermolecular interactions and relative orientations of the molecules. In the retarded regime described by QED and rationalized by stochastic electrodynamics, our analysis shows that field-induced electrostatics and polarization terms remain unchanged (in isotropic and homogeneous vacuum) compared to the non-retarded QM description, in contrast to a recent work. Our framework combining four complementary theoretical approaches paves the way to a systematic description and enhanced understanding of molecular interactions under the combined action of external and vacuum fields.
1 citations
TL;DR: In this article, the authors investigate the system constituted by a polarizable atom near a nanosphere under the influence of an external electrostatic field, showing that the attractive dispersive force between them can be overcome by the electrostatic interaction.
Abstract: We investigate the system constituted by a polarizable atom near a nanosphere under the influence of an external electrostatic field, showing that the attractive dispersive force between them can be overcome by the electrostatic interaction. Therefore, in addition to the advantageous possibility of actively tuning the resultant force with an external agent without the requirement of physical contact, this force may also become repulsive. We analyze this situation in different physical regimes of distance and explore the interaction of different atoms with both metallic and dielectric spheres, discussing which cases are easier to control. Furthermore, our results reveal that these repulsive forces can be achieved with feasible field intensities in the laboratory.
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TL;DR: In this article, the authors present convergence properties of Multipole Expansion of Intermolecular Interaction Operator (MEI) and van der Waals constants (VWC).
Abstract: 1. First-Order (Heitler-London) Exchange 2. Exchange-Induction Interaction 3. Exchange-Dispersion Interaction D. Convergence Properties of Symmetry-Adapted Theories IV. Multipole Expansion of Interaction Energy A. General Asymptotic Expansion of Interaction Energy B. Multipole Expansion of Intermolecular Interaction Operator C. van der Waals Constants D. Convergence Properties of Multipole Expansion of Interaction Energy E. Angular Dependence of Interaction Energy F. Computations of van der Waals Constants Ill. Exchange Effects
2,298 citations
"Comprehensive Quantum Framework for..." refers background in this paper
...[20] B....
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...Interactions between systems ranging from single atoms and small molecules to large macromolecules and nanostructures have been studied extensively in the nonretarded regime within QM framework [20–27]....
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Book•
01 Nov 2016
TL;DR: In this paper, Cartesian tensors and spherical tensors are used to model the intermolecular potentials in the presence of many-body effects and intermolescular forces.
Abstract: Introduction 1. Molecules in Electrostatic Fields 2. Electrostatic Interactions between Molecules 3. Perturbation Theory of Intermolecular Forces at Long Range 4. Ab Initio Methods 5. Perturbation Theory of Intermolecular Forces at Short Range 6. Distributed Multipole Expansions 7. Distributed Polarizabilities 8. Many-body Effects and Intermolecular Forces in Solution 9. Interactions Involving Excited States 10. Practical Models for Intermolecular Potentials 11. Sources of Experimental Data Appendices: A Cartesian Tensors B Spherical Tensors C Introduction to Perturbation Theory D Conversion Factors E Cartesian-Spherical Conversion Tables F Interaction Functions
1,643 citations
Journal Article•
TL;DR: In this paper, the subject of quantum electrodynamics is presented in a new form, which may be dealt with in two ways: using redundant variables and using a direct physical interpretation.
Abstract: THE subject of quantum electrodynamics is extremely difficult, even for the case of a single electron. The usual method of solving the corresponding wave equation leads to divergent integrals. To avoid these, Prof. P. A. M. Dirac* uses the method of redundant variables. This does not abolish the difficulty, but presents it in a new form, which may be dealt with in two ways. The first of these needs only comparatively simple mathematics and is directly connected with an elegant general scheme, but unfortunately its wave functions apply only to a hypothetical world and so its physical interpretation is indirect. The second way has the advantage of a direct physical interpretation, but the mathematics is so complicated that it has not yet been solved even for what appears to be the simplest possible case. Both methods seem worth further study, failing the discovery of a third which would combine the advantages of both.
1,398 citations
"Comprehensive Quantum Framework for..." refers background in this paper
...Such examples include vacuum polarization, self-energy terms, Lamb shift, and even particle creation and annihilation in strong fields [30, 31]....
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