Cold collisions of ground-state calcium atoms in a laser field: A theoretical study
- Laboratoire PALMS, UMR 6627 du CNRS, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, (France)
State-of-the-art ab initio techniques have been applied to compute the potential-energy curves for the ground X {sup 1}{sigma}{sub g}{sup +} and excited {sup 1}{pi}{sub g}(4s3d) states of the calcium dimer in the Born-Oppenheimer approximation. The weakly bound ground state was calculated by symmetry-adapted perturbation theory, while the strongly bound excited state was computed using a combination of the linear-response theory within the coupled-cluster singles and doubles framework for the core-valence electronic correlation and of the full configuration interaction for the valence-valence correlation. The ground-state potential has been corrected by considering the relativistic terms resulting from the first-order many-electron Breit theory, and the retardation corrections. The magnetic electronic transition dipole moment governing the {sup 1}{pi}{sub g}(leftarrow){sup 1}{sigma}{sub g}{sup +} transitions has been obtained as the first residue of the polarization propagator computed with the coupled-cluster method restricted to single and double excitations. The computed energies and transition moments have been analytically fitted and used in the dynamical calculations of the rovibrational energy levels, ground-state scattering length, photoassociation intensities at ultralow temperatures, and spontaneous emission coefficients from the {sup 1}{pi}{sub g}(4s3d) to the X {sup 1}{sigma}{sub g}{sup +} state. The spectroscopic constants of the theoretical ground-state potential are in a good agreement with the experimental values derived from the Fourier-transform spectra [O. Allard et al., Eur. Phys. J. D (to be published)]. The theoretical s-wave scattering length for the ground state is a=44 bohrs, suggesting that it should be possible to obtain a stable Bose-Einstein condensate of calcium atoms. Finally, the computed photoassociation intensities and spontaneous emission coefficients suggest that it should be possible to obtain cold calcium molecules by photoassociation of cold atoms to the first {sup 1}{pi}{sub g} state followed by a spontaneous emission to the ground state.
- OSTI ID:
- 20640192
- Journal Information:
- Physical Review. A, Vol. 68, Issue 3; Other Information: DOI: 10.1103/PhysRevA.68.032718; (c) 2003 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
Similar Records
Formation of ultracold Cs{sub 2} molecules through the double-minimum Cs{sub 2} 3 {sup 1}{sigma}{sub u}{sup +} state
Comparison of the resonance-enhanced multiphoton ionization spectra of pyrrole and 2,5-dimethylpyrrole: Building toward an understanding of the electronic structure and photochemistry of porphyrins
Related Subjects
ATOM-ATOM COLLISIONS
ATOMS
BORN-OPPENHEIMER APPROXIMATION
BOSE-EINSTEIN CONDENSATION
CALCIUM
CONFIGURATION INTERACTION
CORRECTIONS
DIMERS
DIPOLE MOMENTS
ELECTRON CORRELATION
ELECTRONS
EMISSION
EXCITATION
FOURIER TRANSFORMATION
GROUND STATES
LASER RADIATION
MOLECULES
PERTURBATION THEORY
POLARIZATION
POTENTIAL ENERGY
POTENTIALS
PROPAGATOR
RELATIVISTIC RANGE
S WAVES
SCATTERING LENGTHS
SYMMETRY
VALENCE
VIBRATIONAL STATES