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Isotope shifts (ISs) of D1 (ns²Sl/2→np²P1/2) and D2 (ns²S1/2→np²P3/2) transitions for the first three elements of the isoelectronic sequence are calculated with all-order correlated relativistic coupled-cluster theory. To get precise ab initio results, all the orbitals of the reference states have been optimized by a linear regression technique. Some of the important IS estimations reported here were not available in literature. Interesting features of odd-even staggering and magic neutron number effects are also observed in the case of volume shift calculations. Energy-level corrections for a few levels due to a change in the nuclear model from a point nucleus to a Fermi nucleus have been studied with interesting correlation features and compared with other theoretical results available in literature. [ABSTRACT FROM AUTHOR]

We investigate a number of diatomic molecular ions to search for strongly enhanced effects of variation of fundamental constants important for physics beyond the standard model. The relative enhancements due to fine structure and electron-to-proton mass ratio variation occur in transitions between nearly degenerate levels of different nature. Since the trapping techniques for molecular ions have already been developed, the proposed molecules HBr+, HI+, Br2+, I2+, IBr+, IC1+, and IF+ are very promising candidates for future high-resolution experiments. [ABSTRACT FROM AUTHOR]

In this paper, we have calculated parity nonconserving electric dipole amplitudes of the hyperfine components for the transitions between the ground and first excited states of 137Ba+ and 87Sr+ using sum-over-states technique. The results are presented to extract the constants associated with the nuclear spin-dependent amplitudes from experimental measurements. The wave functions to calculate the most dominant part of the sums are constructed using highly correlated coupled-cluster theory based on the Dirac-Coulomb-Gaunt Hamiltonian. [ABSTRACT FROM AUTHOR]

In this paper, we have described electron-correlation trends in the calculations of the hyperfine A and B constants for a few elements belonging to the Na isoelectronic sequence. The hyperfine A and B/Q values of the ground state 3s 2S 1/2 and the excited states 3p 2P 1/2, 3p 2P 1/2, 3d 2D 3/2, and 3d 2D 5/2 of the ions from Si 3+ to V 12+ are presented. The influence of the Breit interaction in the unretarded approximation to these hyperfine values is reported briefly. With increasing atomic number of this sequence, the variations of the different correlation contributing terms such as core correlations, core polarizations, and pair correlations are discussed in the framework of the relativistic coupled-cluster theory. The electron-correlation effect relative to the Dirac-Fock value in the hyperfine A constants of the 3d 2D 3/2,5/2 states follows unusual trends with increasing ionization. The relative pair-correlation effect influences the hyperfine constants of the fine-structure states of a term in an identical way at each species of this sequence. The presented relativistic coupled-cluster results are found to agree excellently with the other available results for a few ions. [ABSTRACT FROM AUTHOR]

In this paper, we study electron correlation and Gaunt interaction effects in ionization potentials (IPs) and hyperfine constants A of 2p2P1/2 and 2p2P3/2 states along with fine structure splitting (FSS) between them for the boron isoelectronic sequence using the relativistic coupled-cluster method. The range of atomic number z is taken from 8 to 21. The Gaunt contributions can be calculated at both the Dirac-Fock and the coupled-cluster levels from our presentation. Calculated IPs and FSS are compared with the results of the National Institute of Standards and Technology. Important correlation contributions like the core correlation, core polarization, and pair correlation effects are studied for hyperfine constants A. Many distinct features of the correlation and relativistic effects are observed in these studies. [ABSTRACT FROM AUTHOR]

The transfer of orbital angular momentum from an optical vortex to an atomic Bose-Einstein condensate changes the vorticity of the condensate. The spatial mismatch between initial and final center-of-mass wave functions of the condensate significantly influences the two-photon optical dipole transition between corresponding states. We show that the transition rate depends on the handedness of the optical orbital angular momentum leading to optical manipulation of matter-wave vortices and circular dichroismlike effect. Based on this effect, we propose a method to detect the presence and sign of matter-wave vortex of atomic superfluids. Only a portion of the condensate is used in the proposed detection method leaving the rest in its initial state. [ABSTRACT FROM AUTHOR]

The exchange of orbital angular momentum between a Laguerre-Gaussian beam of light and the center-of-mass motion of an atom or molecule is well known. We show that the orbital angular momentum of light can also be transferred to the internal electronic or rotational motion of an atom or a molecule provided the internal and center-of-mass motions are coupled. However, this transfer does not happen directly to the internal motion, but via center-of-mass motion. If atoms or molecules are cooled down to the recoil limit, then an exchange of angular momentum between the quantized center-of-mass motion and the internal motion is possible during the interaction of cold atoms or molecules with the Laguerre-Gaussian beam. The orientation of the exchanged angular momentum is determined by the sign of the winding number of the Laguerre-Gaussian beam. We present selective results of numerical calculations for the quadrupole transition rates in the interaction of the Laguerre-Gaussian beam with an atomic Bose-Einstein condensate to illustrate the underlying mechanism of light orbital angular momentum transfer. We discuss how the alignment of diatomic molecules will facilitate exploration of the effects of light orbital angular momentum on the electronic motion of molecules. [ABSTRACT FROM AUTHOR]

Hyperfine constants and anomalies of ground as well as a few low-lying excited states of 113,115,117In III are studied with highly correlated relativistic coupled-cluster theory. The ground-state hyperfine splitting of 115In III is estimated to be 106.8 GHz. A shift of almost 1.9 GHz of the above frequency has been calculated due to the modified nuclear dipole moment. This splitting result shows its applicability as communication band and frequency standards at 10-11 s. A correlation study of hyperfine constants indicates a few distinct features of many-body effects in the wave functions in and near the nuclear region of this ion. Astrophysically important forbidden transition amplitudes are estimated. The calculated oscillator strengths of a few allowed transitions are compared with recent experimental and theoretical results wherever available. [ABSTRACT FROM AUTHOR]

The exchange of orbital angular momentum (OAM) between paraxial optical vortex and a Bose-Einstein condensate (BEC) of atomic gases is well known. In this paper, we develop a theory for the microscopic interaction between matter and an optical vortex beyond paraxial approximation. We show how superposition of vortex states of BEC can be created with a focused optical vortex. Since the polarization or spin angular momentum (SAM) of the optical field is coupled with OAM of the field, in this case, these angular momenta can be transferred to the internal electronic and external center-of-mass motion of atoms provided both the motions are coupled. We propose a scheme for producing the superposition of matter-wave vortices using Gaussian and a focused Laguerre-Gaussian beam. We study how two-photon Rabi frequencies of stimulated Raman transitions vary with focusing angles for different combinations of OAM and SAM of optical states. We demonstrate the formation of vortex-antivortex structure and discuss interference of three vortex states in a BEC. [ABSTRACT FROM AUTHOR]

This work presents accurate ab initio investigations of various spectroscopic properties of a few Li-like ions in the presence, of a plasma environment within the Debye screening potential. The coupled-cluster theory in the relativistic framework has been employed to compute ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities of Li-like C3+, N4+, and O5+ ions. The unretarded Breit interaction has been implemented to increase the accuracy of the calculations. The effects of ion density and temperature on the ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities have been investigated in the plasma environment. It is found that the plasma screening leads to a sharp decrease in the ionization potential as the screening strength increases. With increasing strength, the oscillator strengths associated with 2s ²S1/2 2p² P1/2,3/2 transitions increase, whereas . the transition probabilities associated with 3d ²D3/2,5/2 2s2S1/2 transitions decrease. [ABSTRACT FROM AUTHOR]

In this paper, the El, £2, and Ml transition amplitudes are calculated along with the hyperfine A and B constants of doubly ionized gallium using the relativistic coupled-cluster approach. Electron correlations and the Gaunt interactions are considered to all orders using the coupled-cluster theory in a relativistic framework and their contributions are discussed explicitly in the calculations of all these amplitudes. Some interesting features of the correlation effects on the Gaunt interactions are noticed in the calculations of the hyperfine constants. The lifetimes of some low-lying states are also calculated using the transition amplitudes obtained by the present theory and the experimental transition energies. The calculated El transition amplitudes and lifetimes are in good agreement with the results obtained by the other theories and experiment. The hyperfine splitting of the ground states of In this paper, the El, £2, and Ml transition amplitudes are calculated along with the hyperfine A and B constants of doubly ionized gallium using the relativistic coupled-cluster approach. Electron correlations and the Gaunt interactions are considered to all orders using the coupled-cluster theory in a relativistic framework and their contributions are discussed explicitly in the calculations of all these amplitudes. Some interesting features of the correlation effects on the Gaunt interactions are noticed in the calculations of the hyperfine constants. The lifetimes of some low-lying states are also calculated using the transition amplitudes obtained by the present theory and the experimental transition energies. The calculated El transition amplitudes and lifetimes are in good agreement with the results obtained by the other theories and experiment. The hyperfine splitting of the ground states of 71Ga m and 69Ga III are found to be about 35 and 27.5 GHz, respectively, which shows the importance of these isotopes for the possible use of microwave frequency standards. The calculated hyperfine constants are associated with linewidth estimations of some transition lines in the visible and ultraviolet regions of electromagnetic spectrum. [ABSTRACT FROM AUTHOR]