Search results for " DIP"

A Tensorial Formalism Adapted to the Rovibronic Couplings in the Colored Hexafluorides: Application to the nu(5)(F(2g)) and nu(3)(F(1u)) Modes.

2000

A tensorial formalism adapted to the case of transition-metal hexafluorides in a degenerate electronic state has been developed on the basis of preceding works about spherical-top molecules in a nondegenerate electronic state. We have introduced electronic operators constructed using group theory features and some physical considerations. Vibronic couplings (Jahn-Teller effect, etc.) have been reviewed for the triply degenerate vibrational modes nu(5)(F(2g)) and nu(3)(F(1u)) leading to the identification of the main vibronic parameters. For the first time, an effective rovibronic Hamiltonian as well as the effective transition moment operators (dipole moment and polarizability) for rovibron…

Comment on "Axion induced oscillating electric dipole moments"

2017

In the recent work [Phys. Rev. D 91, 111702(R) (2015)], C. Hill concludes that the axion electromagnetic anomaly induces an oscillating electron electric dipole moment of frequency $m_a$ and strength $\sim 10^{-32}~e$ cm, in the limit $v/c \to 0$ for the axion field. Here, we demonstrate that a proper treatment of this problem in the lowest order yields $\textit{no}$ electric dipole moment of the electron in the same limit. Instead, oscillating electric dipole moments of atoms and molecules are produced by different mechanisms.

Relativistic corrections to electrical first-order properties using direct perturbation theory.

2008

Direct perturbation theory (DPT) is applied to compute relativistic corrections to electrical properties such as dipole moment, quadrupole moment, and electric-field gradient. The corrections are obtained as second derivatives of the energy and are given via method-independent expressions that involve the first derivative of the density matrix with respect to the relativistic perturbation as well as property integrals with additional momentum operators. Computational results obtained using Hartree-Fock (HF), second-order Moller-Plesset (MP2) perturbation theory, and the coupled-cluster singles and doubles approach augmented by a perturbative treatment of triple excitations are presented for…

Quasirelativistic transition property calculations by the intermediate Hamiltonian method: Electronic transition dipole moments and radiative lifetim…

2001

We present a quasirelativistic method of ab initio calculations on molecular excited states and electronic transition moments within the relativistic effective potential approximation, based on the construction of intermediate Hamiltonians and spin-free one-particle transition density matrices by means of the many-body multipartitioning perturbation theory. The method is applied to describe the electronic transitions involved in the radiative decay of the ${A0}_{u}^{+},$ ${B0}_{u}^{+},$ and ${B1}_{u}$ states of ${\mathrm{Te}}_{2}.$ Good agreement of the computed transition dipole moment functions with their empirical counterparts is achieved. Theoretical radiative lifetime estimates for sev…

Lowest- Q2 measurement of the γp → Δ reaction: Probing the pionic contribution

2006

To determine nonspherical angular momentum amplitudes in hadrons at long ranges (low Q^2), data were taken for the p(\vec{e},e'p)\pi^0 reaction in the Delta region at Q^2=0.060 (GeV/c)^2 utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The results for the dominant transition magnetic dipole amplitude and the quadrupole to dipole ratios at W=1232 MeV are: M_{1+}^{3/2} = (40.33 +/- 0.63_{stat+syst} +/- 0.61_{model}) (10^{-3}/m_{\pi^+}),Re(E_{1+}^{3/2}/M_{1+}^{3/2}) = (-2.28 +/- 0.29_{stat+syst} +/- 0.20_{model})%, and Re(S_{1+}^{3/2}/M_{1+}^{3/2}) = (-4.81 +/- 0.27_{stat+syst} +/- 0.26_{model})%. These disagree with predictions of constituent quark models but are in reaso…

Dipole moments of aminophthalimides in the ground and excited electronic states

1995

Experimental and theoretical study of thenf-level lifetimes of potassium

2008

The theoretical and experimental values of the 5f ,6 f ,7 f, and 8f radiative lifetimes of neutral potassium are reported. The reduced matrix elements for all allowed electric-dipole nf5/2-nd5/2, nf5/2-nd3/2, and nf7/2-nd5/2 transitions with n =5–8 in K arecalculated using the relativistic linearized coupled-cluster method with single and double excitations of Dirac-Fock wave functions included to all orders in many-body perturbation theory. The resulting electric-dipole matrix elements are used to evaluate the lifetimes of the 5f ,6 f ,7 f, and 8f states in neutral K and their uncertainties. The contributions from the nf5/2-ng7/2, nf7/2-ng7/2, and nf7/2-ng9/2 transitions to the lifetimes o…

Evidence for Three Microscopically Different Kinds of E1 Transitions in Lead-Region Nuclei

1986

One outstanding feature of the shell model in heavy nuclei is that within a main shell the single-particle transitions of electric dipole (E1) character are forbidden. This leads to the experimentally observed fact that the E1 transitions are usually hindered by a factor of about 10 with respect to the Weisskopf estimate. But since there is a dispersion of about two or three orders of magnitude among these hindrance factors, the isomeric E1 transitions have not been used to elucidate the mocroscopic properties of the involved states, as has been done for the E3 transitions of this nuclear region [1]. The E3 transitions often proceed via admixtures of the low-lying collective octupole state,…

Measurement of the Dipole Polarizability of the Unstable Neutron-Rich NucleusNi68

2013

The E1 strength distribution in Ni68 has been investigated using Coulomb excitation in inverse kinematics at the RB3-LAND setup and by measuring the invariant mass in the one- and two-neutron decay channels. The giant dipole resonance and a low-lying peak (pygmy dipole resonance) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic random phase approximation calculations yielding a neutron-skin thickness of 0.17(2) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.

Complete Electric Dipole Response and the Neutron Skin inPb208

2011

A benchmark experiment on Pb-208 shows that polarized proton inelastic scattering at very forward angles including 0 degrees is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted E1 polarizability leads to a neutron skin thickness r(skin) = 0.156(-0.021)(+0.025) fm in Pb-208 derived within a mean-field model [Phys. Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its density dependence relevant to the description of neutron stars.