Sympathetic cooling of the Ba{sup +} ion by collisions with ultracold Rb atoms: Theoretical prospects
- Institute of Theoretical Physics, Department of Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland) and Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw (Poland)
State-of-the-art ab initio techniques have been applied to compute the potential energy curves of the (BaRb){sup +} molecular ion in the Born-Oppenheimer approximation for the singlet and triplet states dissociating into the ground-state {sup 1}S Rb{sup +} ion and the Ba atom in the ground {sup 1}S state or the lowest singlet or triplet d excited states, and for the singlet and triplet states dissociating into the ground-state {sup 2}S Rb atom and the ground-state {sup 2}S Ba{sup +} ion. The ground-state potential energy was obtained with the coupled-cluster method restricted to single, double, and nonperturbative triple excitations. The first triplet states in the {Sigma}, {Pi}, and {Delta} symmetries were computed with the restricted open-shell coupled-cluster method restricted to single, double, and nonperturbative triple excitations. All other excited-state potential energy curves were computed using the equation of motion approach within the coupled-cluster singles, doubles, and linear triples framework. The long-range coefficients describing the electrostatic, induction, and dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments governing the x {sup 1{Sigma}{yields}1{Sigma}},{sup 1{Pi}} transitions have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Nonadiabatic radial and angular coupling matrix elements as well as the spin-orbit coupling matrix elements have been evaluated using the multireference configuration-interaction method restricted to single and double excitations with a large active space. With these couplings, the spin-orbit-coupled (relativistic) potential energy curves for the 0{sup +} and 1 states relevant for the running experiments have been obtained. Finally, relativistic transition moments and nonadiabatic coupling matrix elements were obtained from the nonrelativistic results and spin-orbit eigenvectors. The electronic structure input has been employed in the single-channel scattering calculations of the collisional cross sections between the Ba{sup +} ion and Rb atom. Both nonrelativistic and relativistic potentials were used in these calculations. Our results show that the inelastic cross section corresponding to the charge transfer from the Rb atom to the Ba{sup +} ion is much smaller than the elastic one over a wide range of energies up to 1 mK. This suggests that sympathetic cooling of the Ba{sup +} ion by collisions with ultracold Rb atoms should be possible.
- OSTI ID:
- 21541301
- Journal Information:
- Physical Review. A, Vol. 83, Issue 3; Other Information: DOI: 10.1103/PhysRevA.83.032723; (c) 2011 American Institute of Physics; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM IONS
BORN-OPPENHEIMER APPROXIMATION
CONFIGURATION INTERACTION
CROSS SECTIONS
DIPOLE MOMENTS
EIGENVECTORS
ELECTRONIC STRUCTURE
EQUATIONS OF MOTION
EXCITED STATES
INTERATOMIC DISTANCES
L-S COUPLING
MATRIX ELEMENTS
MOLECULAR IONS
POLARIZATION
POTENTIAL ENERGY
PROPAGATOR
RELATIVISTIC RANGE
RUBIDIUM IONS
TRIPLETS
APPROXIMATIONS
CALCULATION METHODS
CHARGED PARTICLES
COUPLING
DIFFERENTIAL EQUATIONS
DISTANCE
ENERGY
ENERGY LEVELS
ENERGY RANGE
EQUATIONS
INTERMEDIATE COUPLING
IONS
MULTIPLETS
PARTIAL DIFFERENTIAL EQUATIONS