scholarly journals Electronic Currents and Anapolar Response Induced in Molecules by Monochromatic Light

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 1022-1036
Author(s):  
Francesco Ferdinando Summa ◽  
Paolo Lazzeretti
Keyword(s):  
Numerical Integration ◽  
Electric Dipole ◽  
Monochromatic Light ◽  
Electric Quadrupole ◽  
Computational Techniques ◽  
Optical Fields ◽  
Electronic Current ◽  
Chiral Species ◽  
Preliminary Computation ◽  
Preliminary Application

It is shown that the electric dipole- and electric quadrupole–anapole polarizabilities, denoted respectively by fαβ′ and gα,βγ′, and the anapole magnetizability aαβ, are intrinsic properties of the electron cloud of molecules responding to optical fields. fαβ′ is a nonvanishing property of chiral and achiral compounds, whereas aαβ is suitable for enantiomer discrimination of chiral species. They can conveniently be evaluated by numerical integration, employing a formulation complementary to that provided by perturbation theory and relying on the preliminary computation of electronic current density tensors all over the molecular domain. The origin dependence of the dynamic anapolar response is rationalized via related computational techniques employing numerical integration, as well as definitions of molecular property tensors, for example, electric dipole and electric quadrupole polarizabilties and magnetizability. A preliminary application of the theory is reported for the Ra enantiomer of the hydrogen peroxide molecule, evaluating tensor components of electric dipole-anapole polarizability and anapole magnetizability as functions of the dihedral angle ϕ≡∠ H-O-O-H in the range 0∘≤ϕ≤180∘.

A High-Resolution Linelist for Molecular Oxygen

2020 ◽  
Author(s):  
Wilfrid Somogyi ◽  
Sergey Yurchenko
Keyword(s):  
High Resolution ◽  
Molecular Oxygen ◽  
Electric Dipole ◽  
Electric Quadrupole ◽  
Dipole Approximation ◽  
Higher Order ◽  
Computational Techniques ◽  
Absorption Bands ◽  
Path Lengths ◽  
Homonuclear Diatomic Molecules

<p>Molecular oxygen (O<sub>2</sub>) is of particular interest in exoplanetary observations not least of all as an important biosignature on habitable planets. The atmospheric absorption bands are well studied, but a complete and accurate, high-resolution linelist is yet to be produced. Owing to their symmetry, the commonly employed electric dipole approximation is not valid for homonuclear diatomic molecules, and their rovibrational spectra are instead dominated by higher order transitions moments. These higher-order moments, such as the electric quadrupole and magnetic dipole, give rise to transition linestrengths that are orders of magnitude weaker than typical electric dipole transitions. Although such transitions are observable for atmospheric path lengths, their weak nature makes laboratory measurements especially challenging. In this work we develop and apply ab initio computational techniques to produce an accurate electric quadrupole spectrum of molecular oxygen presented for use in atmospheric retrievals across a range of temperatures, and made available through the ExoMol database.</p>

Full Optical Rotation Tensor at CCSD Level in the Modified Velocity Gauge

2020 ◽  
Author(s):  
Kaihua Zhang ◽  
Ty Balduf ◽  
Marco Caricato
Keyword(s):  
Electric Dipole ◽  
Optical Rotation ◽  
Electric Quadrupole ◽  
Polarizability Tensor ◽  
Dipole Polarizability ◽  
Difficult Case ◽  
Computationally Efficient ◽  
Rotation Tensor ◽  
Approximate Methods ◽  
Velocity Gauge

<div> <div> <p> </p><div> <div> <div> <p>This work presents the first simulations of the full optical rotation (OR) tensor at coupled cluster with single and double excitations (CCSD) level in the modified velocity gauge (MVG) formalism. The CCSD-MVG OR tensor is origin independent, and each tensor element can in principle be related directly to experimental measurements on oriented systems. We compare the CCSD results with those from two density functionals, B3LYP and CAM-B3LYP, on a test set of 22 chiral molecules. The results show that the functionals consistently overestimate the CCSD results for the individual tensor components and for the trace (which is related to the isotropic OR), by 10-20% with CAM-B3LYP and 20-30% with B3LYP. The data show that the contribution of the electric dipole-magnetic dipole polarizability tensor to the OR tensor is on average twice as large as that of the electric dipole-electric quadrupole polarizability tensor. The difficult case of (1S,4S)-(–)-norbornenone also reveals that the evaluation of the former polarizability tensor is more sensitive than the latter. We attribute the better agreement of CAM-B3LYP with CCSD to the ability of this functional to better reproduce electron delocalization compared with B3LYP, consistently with previous reports on isotropic OR. The CCSD-MVG approach allows the computation of reference data of the full OR tensor, which may be used to test more computationally efficient approximate methods that can be employed to study realistic models of optically active materials. </p> </div> </div> </div> </div> </div>

Electromagnetic radiation

2018 ◽  
Author(s):  
J. Pierrus
Keyword(s):  
Electromagnetic Radiation ◽  
Magnetic Dipole ◽  
Antenna Arrays ◽  
Electric Dipole ◽  
Free Electron ◽  
Vector Potential ◽  
Electric Quadrupole ◽  
Multipole Expansion ◽  
Multipole Moments

This chapter begins by expressing the multipole expansion of the dynamic vector potential A ( r, t) in terms of electric and magnetic multipole moments. Differentiation of A ( r, t) leads directly to the fields E ( r, t) and B ( r, t), which have a component transporting energy away from the sources to infinity. This component is called electromagnetic radiation and it arises only when electric charges experience an acceleration. A range of questions deal with the various types of radiation, including electric dipole and magnetic dipole–electric quadrupole. Larmor’s formula is applied in both its non-relativistic and relativistic forms. Also considered are some applications involving antennas, antenna arrays and the scattering of radiation by a free electron.

scholarly journals Enhancement of and interference among higher order multipole transitions in molecules near a plasmonic nanoantenna

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Evgenia Rusak ◽  
Jakob Straubel ◽  
Piotr Gładysz ◽  
Mirko Göddel ◽  
Andrzej Kędziorski ◽  
...  
Keyword(s):  
Spontaneous Emission ◽  
Electric Dipole ◽  
Electric Quadrupole ◽  
Coherence Time ◽  
Dipole Approximation ◽  
Higher Order ◽  
Destructive Interference ◽  
Interference Effects ◽  
Matter Coupling ◽  
Molecular Transition

AbstractSpontaneous emission of quantum emitters can be modified by their optical environment, such as a resonant nanoantenna. This impact is usually evaluated under assumption that each molecular transition is dominated only by one multipolar channel, commonly the electric dipole. In this article, we go beyond the electric dipole approximation and take light-matter coupling through higher-order multipoles into account. We investigate a strong enhancement of the magnetic dipole and electric quadrupole emission channels of a molecule adjacent to a plasmonic nanoantenna. Additionally, we introduce a framework to study interference effects between various transition channels in molecules by rigorous quantum-chemical calculations of their multipolar moments and a consecutive investigation of the transition rate upon coupling to a nanoantenna. We predict interference effects between these transition channels, which allow in principle for a full suppression of radiation by exploiting destructive interference, waiving limitations imposed on the emitter’s coherence time by spontaneous emission.

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