Dynamic Dipole Polarizabilities Research Articles

Dynamic and static dipole polarizability of an Aharonov–Bohm ring

The properties of nanoscale rings are sensitive to Aharonov–Bohm fluxes threading the ring. In particular, neighboring angular momentum eigenstates become degenerate in cases of half-integer flux. Such degeneracies have a profound effect on the dipole polarizability leading to a divergent response. We analyze circular finite-width nanorings and derive a simple and compact expression for the polarizability valid for arbitrary ring geometry, frequency and magnetic flux. The dipole response is significantly reduced by finite-width effects, yet divergencies at half-integer flux are predicted irrespective of width. Finally, a non-divergent (but large) response is restored through a non-perturbative treatment of both magnetic and electric fields.

Polarizabilities of the negative ions of hydrogen and positronium in nonideal classical plasmas

We investigate the polarizability of the negative ions of hydrogen and positronium embedded in nonideal classical plasmas using correlated exponential wavefunctions. The interactions among the charged particles in plasmas have been taken care of by a pseudopotential, derived from a solution of Bogolyubov's hierarchy equations. The effects of nonideality of plasma on the ground state energies and the static and dynamic dipole polarizabilities of the negative ions have been studied in detail for wide range of nonideality. The results show interesting features.

Non-ideal classical plasma: laser pulse effects and dynamic dipole polarizabilities

The properties of a hydrogen atom inside a non-ideal classical plasma, in terms of its behavior in the presence of an applied laser pulse, are explored. The strength of the pulse is chosen such that it maintains near sphericity of the system. The pulse parameters have a strong bearing on the final state attained by the system after its interaction with the pulse. Dynamic dipole polarizability is calculated and the poles are observed to be red shifted with an increase in non-ideality as well as an increase in plasma temperature. The polarizabilities for frequencies of the field below the frequency corresponding to the first pole are found to be greater for larger values of field frequency, plasma non-ideality and electron plasma temperature.

Origin-Independent Dynamic Polarizability Density from Coupled Cluster Response Theory.

The calculation of the origin-independent density of the dynamic electric dipole polarizability, previously presented for uncorrelated and density functional theory (DFT)-based methods, has been developed and implemented at the coupled cluster singles and doubles (CCSD) level of theory. A pointwise analysis of polarizability densities calculated for a number of molecules at Hartree-Fock (HF) and CCSD clearly shows that the electron correlation effect is much larger than one would argue considering the integrated dipole electric polarizability alone. Large error compensations occur during the integration process, which hide fairly large deviations mainly located in the internuclear regions. The same is observed when calculated CCSD and B3LYP polarizability densities are compared, with the remarkable feature that positive/negative deviations between CCSD and HF reverse sign, becoming negative/positive when comparing CCSD to B3LYP.

Magic wavelengths for 6s1/2 → 5d3/2,5/2 transitions of Yb+ ions

The wave functions, energy levels and matrix elements of Yb+ ions are calculated using the relativistic configuration interaction plus core polarization (RCICP) method. The static and dynamic electric dipole polarizabilities of the ground state and low-lying excited states are determined. Then, the magic wavelengths of the magnetic sublevel 6s1/2,m = 1/2 → 5d3/2,m = ±3/2,±1/2 and 6s1/2,m = 1/2 → 5d5/2,m = ±5/2,±3/2,±1/2 transitions in the linearly, right-handed, and left-handed polarized light are further determined. The dependence of the magic wavelengths upon the angle between the direction of magnetic field and the direction of laser polarization is analyzed.

FitAik: A package to calculate least-square fitted atomic transitions probabilities

We present a new method implemented in our new package FitAik, to perform least-squares fitting of calculated and experimental atomic transition probabilities, by using the mono-electronic transition integrals 〈nℓ|r|n′ℓ′〉 (with r the electronic radial coordinate) as adjustable quantities. FitAik is interfaced to the Cowan suite of codes, for which it automatically writes input files and reads output files. We illustrate our procedure with the example of Er+ ion, for which the agreement between calculated and experimental Einstein coefficients is found to be very good. The source code of FitAik can be found on GitLab, and the calculated Einstein coefficients are stored in our new database CaDDiAcS. They are also used to calculate the dynamic dipole polarizability of Er+.

Polarizabilities for the low-lying triplet states of He-like Be III

The nonrelativistic and relativistic full-configuration-interaction calculations are performed for the low-lying triplet states of Be2+ ion. The energies for n3S1, n3PJ and n3DJ states, and the dipole oscillator strengths for the 23S1(33S1)→n3PJ and 23PJ(33PJ)→n3DJ transitions with the main quantum number n up to 5 are determined. We calculate the nonrelativistic dynamic dipole polarizabilities by using the sum rule of intermediate states. In addition, the tune-out wavelengths for the four lowest triplet states and magic wavelengths for the 23S→23P and 23S→33P transitions are obtained.

Tune-out wavelengths for the 2 3S1 state of the Li+ ion

Configuration interaction calculations are performed to determine the dipole polarizabilities and tune-out wavelengths for the $2{\phantom{\rule{0.28em}{0ex}}}^{3}{S}_{1}$ state in ${\mathrm{Li}}^{+}$ ion. The finite nuclear mass correction is given by including the mass shift operator in the Dirac-Coulomb-Breit Hamiltonian directly, while the QED correction to dynamic dipole polarizabilities is evaluated by using the perturbation theory. The tune-out wavelengths for the $2{\phantom{\rule{0.28em}{0ex}}}^{3}{S}_{1}\phantom{\rule{0.28em}{0ex}}({M}_{J}=0)$ and $2{\phantom{\rule{0.28em}{0ex}}}^{3}{S}_{1}\phantom{\rule{0.28em}{0ex}}({M}_{J}=\ifmmode\pm\else\textpm\fi{}1)$ states are 159.620 55(6) nm and 159.631 14(6) nm, respectively. And the QED correction for 159 nm tune-out wavelength is 43 ppm. In addition, we obtain the static dipole polarizability for the $2{\phantom{\rule{0.28em}{0ex}}}^{3}{S}_{1}\phantom{\rule{0.28em}{0ex}}({M}_{J}=\ifmmode\pm\else\textpm\fi{}1)$ state to be 46.857 03(4) a.u., in which the contribution from QED is 70 ppm. The 159 nm tune-out wavelength and the static dipole polarizability of $2{\phantom{\rule{0.28em}{0ex}}}^{3}{S}_{1}$ state might provide a test of atomic structure theory.

Laser measurements of static and dynamic dipole polarizability for 11 metal atoms using fast exploding wires in vacuum and integrated-phase technique

The rapid electrical explosion of thin metal wires in a vacuum can completely vaporize the wire and form a fast-expanding gas cylinder of metal atoms. Thin metal wires 12.7 μm in diameter made of W, Mo, Pt, Pd, Ni, Cu, Au, and Al completely evaporated during the first ∼10 ns under the action of a fast-rising current of ∼1 kA/ns. Laser interferometry and the integrated phase technique were used to reconstruct the dynamic atomic polarizability for fully vaporized thin metal wires at 532 and 1064 nm wavelength, calculate the static atomic polarizability, the first dipole-allowed electronic transition energy, and transition wavelengths, and compare our reconstructions with available tabulated values.

Two-dipole and three-dipole interaction coefficients of group XII elements

Study of long-range interactions is increasingly becoming essential due to its various applications in cold atomic physics. These interactions can be conveniently expressed in terms of various dispersion coefficients. In the present work, theoretical calculations have been carried out for the two-dipole (C6), and three-dipole (C9) dispersion coefficients among the group XII atoms and their ions, viz. Zn, Cd, Hg, Zn+, Cd+, and Hg+. To obtain these coefficients, the dynamic dipole polarizabilities and reduced matrix elements required are evaluated using the relativistic methods. Further, using the calculated matrix elements, the oscillator strengths corresponding to leading transitions and static dipole polarizabilities of these atoms and ions are determined for the comparison purposes.

Dispersion C3 coefficients for physisorption of heavy ions and atoms with graphene and carbon nanotubes

In the present work, the calculations have been performed for dispersion interaction between heavy elements $({\mathrm{Zn}}^{+},$ ${\mathrm{Cd}}^{+},$ ${\mathrm{Hg}}^{+},$ ${\mathrm{Pb}}^{+}, \mathrm{Zn}, \mathrm{Cd}, \mathrm{Hg}, \mathrm{and} \mathrm{Pb})$ with graphene and carbon nanotubes by evaluating van der Waals ${C}_{3}$ coefficients using the well-known Lifshitz theory. The dispersion coefficients are expressed in terms of reflection coefficients of graphene and carbon nanotubes which are calculated within the framework of the Dirac model. In addition, accurate values of dynamic dipole polarizabilities at imaginary frequencies of considered ions and atoms which are vital have been calculated using relativistic methods. The comparisons of our calculated static dipole polarizabilities for the considered elements with the values reported in the literature are also presented. The dispersion interactions of the considered heavy elements with the graphene and carbon nanotubes of different radii in a wide range of separation distances have been studied. The results have also been analyzed with another subtle variable, i.e., the gap parameter of the graphene wall. The interaction coefficients obtained for both the materials, i.e., for graphene and carbon nanotubes, are mutually compared and it is found that graphene can be said to be a preferable material for adsorption of these toxic heavy elements.

Few-Neutron Systems with the Long-Range Casimir-Polder Force

In this work we present results of the long-range electromagnetic Casimir-Polder interactions between two neutrons, a neutron and a conducting wall, and a neutron between two walls. As input, we use the dynamic dipole polarizabilities of the neutron fitted to chiral EFT results up to the pion production threshold and at the onset of the Delta resonance. Our work can be relevant to the physics of confined ultracold neutrons inside bottles.

Magic Wavelengths for Optical-Lattice Based Cs and Rb Active Clocks

Active clocks could provide better stabilities during initial stages of measurements over passive clocks, in which stabilities become saturated only after long-term measurements. This unique feature of an active clock has led to search for suitable candidates to construct such clocks. The other challenging task of an atomic clock is to reduce its possible systematics. A major part of the optical lattice atomic clocks based on neutral atoms are reduced by trapping atoms at the magic wavelengths of the optical lattice lasers. Keeping this in mind, we find the magic wavelengths between all possible hyperfine levels of the transitions in Rb and Cs atoms that were earlier considered to be suitable for making optical active clocks. To validate the results, we give the static dipole polarizabilities of Rb and Cs atoms using the electric dipole transition amplitudes that are used to evaluate the dynamic dipole polarizabilities and compare them with the available literature values.

Van der Waals coefficients of the multi-layered MoS2 with alkali metals

The van der Waals coefficients and the separation dependent retardation functions of the interactions between the atomically thin films of the multi-layered transition metal molybdenum disulfide (MoS2) dichalcogenides with the alkali atoms are investigated. First, we determine the frequency-dependent dielectric permittivity and intrinsic carrier density values for different layers of MoS2 by adopting various fitting models to the recently measured optical data reported by Yu and co-workers (2015 Sci. Rep. 5, 16 996) using spectroscopy ellipsometry. Then, dynamic electric dipole polarizabilities of the alkali atoms are evaluated very accurately by employing the relativistic coupled-cluster theory. We also demonstrate the explicit change in the above coefficients for different number of layers. These studies are highly useful for the optoelectronics, sensing and storage applications using layered MoS2.

Two-dipole and three-dipole dispersion coefficients for interaction of alkaline-earth-metal atoms with alkaline-earth-metal atoms and alkaline-earth-metal ions

Apropos of the growing interest in the study of long-range interactions for their applications in cold-atom physics, we perform theoretical calculations for the two-dipole ${C}_{6}$ and three-dipole ${C}_{9}$ dispersion coefficients involving alkaline-earth-metal atoms with alkaline-earth-metal atoms and alkaline-earth-metal ions. The ${C}_{6}$ and ${C}_{9}$ coefficients are expressed in terms of the dynamic dipole polarizabilities, which are calculated using relativistic methods. Thereafter, the calculated ${C}_{6}$ coefficients for the considered alkaline-earth-metal atoms are compared with previously reported values. Due to unavailability of any other earlier theoretical or experimental results, for the ${C}_{6}$ coefficients for alkaline-earth-metal atoms with alkaline-earth-metal ions and the ${C}_{9}$ coefficients we perform separate fitting calculations and compare the results. Our calculations match in an excellent manner with the fitting calculations. We also report the oscillator strengths for the leading transitions and static dipole polarizabilities for the ground states of the alkaline-earth-metal ions, i.e., ${\mathrm{Be}}^{+}, {\mathrm{Mg}}^{+}, {\mathrm{Ca}}^{+}, {\mathrm{Sr}}^{+}$, and ${\mathrm{Ba}}^{+}$, as well as the alkaline-earth-metal atoms, i.e., Be, Mg, Ca, Sr, and Ba. These show good agreement when compared with the available experimental results.

Extended combination rule for like-atom dipole dispersion coefficients.

An extended combination rule is proposed to relate the dipole-dipole dispersion coefficient for the interaction of the like target species to the same coefficients for the interactions between the target and a set of partner species. The rule can be derived either by uniform discretization of the Casimir-Polder integral on a quadrature or by relating the dynamic dipole polarizabilities of the target species and the partner species. Both methods result in the same system of linear equations, whose solution also requires the knowledge of the dispersion coefficients for interaction between the partner species. The test examples indicate a high accuracy of the proposed rule for dispersion coefficients (better than 1% in the stringent test for the Yb atom interacting with a rare gas and alkaline-earth metal atoms). However, the combination rule does not warrant correct approximation of the dynamic polarizability of the target species.

Spectroscopic and theoretical optical properties of indoleninyl‐substituted dibenzotetraaza[14]annulenes

AbstractTwo new macrocyclic dibenzotetraaza[14]annulene (DBTAA) compounds with indolenine (5) and pyridoindolenine (6) moieties were synthesized and characterized by spectroscopy. Both DBTAAs exhibit strong UV‐Vis absorption properties in the Soret band region. The theoretical second‐order nonlinear optical property, electric dipole moment (μ), dispersion‐free dipole polarizability (α) and first hyper‐polarizability values were calculated by density functional theory and time dependent density functional theory. The ab‐initio quantum mechanical calculation by time‐dependent Hartree‐Fock method was utilized to investigate the dynamic dipole polarizabilities, dynamic second‐order, static, and dynamic third‐order (γ) hyper‐polarizabilities of the DBTAAs. The configuration interaction technique of all doubly occupied molecular orbitals possesses theoretically defined single‐photon absorption (OPA) specifications for the examined structures. The computed maximum OPA wavelengths on both macrocyclic compounds coincide with the preceding measurement outcomes.

Polarizabilities and tune-out wavelengths of the hyperfine ground states of 133Cs atom

SynopsisThe static and dynamic electric dipole polarizabilities of the ground state and hyperfine ground states of the 133Cs have been calculated by using relativistic configuration interaction plus core polarization (RCICP) approach. The tune-out wavelengths of ground and hyperfine ground states are also determined.

Relativistic configuration interaction with core polarization method for the divalent systems

SynopsisThe relativistic configuration interaction with core polarization method and program for the divalent systems have been developed. Based on this new program, the energy levels, transition matrix elements, static and dynamic dipole polarizabilities of He, Be, and Mg atoms have been calculated systematically.

Interferometric measurements of static and dynamic dipole polarizability of titanium atoms using fast electrical explosion of fine metal wires in vacuum

The rapid electrical explosion of fine metal wires in vacuum generates gas cylinders of metal atoms surrounded by low-density and fast-expanding plasma corona. For fully vaporized wires, we utilize the integrated-phase technique, based on laser interferometry, to measure the dynamic dipole polarizability of metal atoms. Titanium wire with a diameter of 20 μm and a length of 1 cm was rapidly vaporized by a fast-rising current at ∼10 ns. We find that the dynamic dipole polarizability of titanium atoms equals 20.5 ± 2 Å3 for 532 nm and 10.6 ± 1 Å3 for 1064 nm. The wire reaches a totally vaporized state when the expansion velocity in a vacuum is ∼5.5 km/s. To vaporize Ti wire, the deposited Joule energy exceeded tabulated enthalpy of atomization by ∼2.8 times. Two-wavelength diagnostic allows reconstruction of the static dipole polarizability 9.13 ± 1.7 Å3 and electron transition energy 3.13 ± 0.2 eV with the corresponding transition wavelength of 396.6 ± 26 nm. This reconstructed wavelength matches to the group of strong dipole-allowed atomic spectral lines for Ti between 394.87 and 402.46 nm for ground-state transitions 3d24s2.