M Aymar

Calculation of accurate permanent dipole moments of the lowest Σ+1,3 states of heteronuclear alkali dimers using extended basis sets

Obtaining ultracold samples of dipolar molecules is a current challenge which requires an accurate knowledge of their electronic properties to guide the ongoing experiments. In this paper, we systematically investigate the ground state and the lowest triplet state of mixed alkali dimers (involving Li, Na, K, Rb, Cs) using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective terms for core polarization effects. We emphasize on the convergence of the results for permanent dipole moments regarding the size of the Gaussian basis set, and we discuss their predicted accuracy by comparing to other theoretical calculations or available experimental values. We also revisit the difficulty to compare computed potential curves among published papers, due to the differences in the modelization of core-core interaction.

Calculations of static dipole polarizabilities of alkali dimers: Prospects for alignment of ultracold molecules

The rapid development of experimental techniques to produce ultracold alkali molecules opens the ways to manipulate them and to control their dynamics using external electric fields. A prerequisite quantity for such studies is the knowledge of their static dipole polarizability. In this paper, we computed the variations with internuclear distance and with vibrational index of the static dipole polarizability components of all homonuclear alkali dimers including Fr(2), and of all heteronuclear alkali dimers involving Li to Cs, in their electronic ground state and in their lowest triplet state. We use the same quantum chemistry approach as in our work on dipole moments [Aymar and Dulieu, J. Chem. Phys. 122, 204302 (2005)], based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective potentials for core polarization. Polarizabilities are extracted from electronic energies using the finite-field method. For the heaviest species Rb(2), Cs(2), and Fr(2) and for all heteronuclear alkali dimers, such results are presented for the first time. The accuracy of our results on atomic and molecular static dipole polarizabilities is discussed by comparing our values with the few available experimental data and elaborate calculations. We found that for all alkali pairs, the parallel and perpendicular components of the ground state polarizabilities at the equilibrium distance R(e) scale as (R(e))(3), which can be related to a simple electrostatic model of an ellipsoidal charge distribution. Prospects for possible alignment and orientation effects with these molecules in forthcoming experiments are discussed.

Light-Assisted Ion-Neutral Reactive Processes in the Cold Regime: Radiative Molecule Formation versus Charge Exchange

We present a combined experimental and theoretical study of cold reactive collisions between laser-cooled Ca+ ions and Rb atoms in an ion-atom hybrid trap. We observe rich chemical dynamics which are interpreted in terms of nonadiabatic and radiative charge exchange as well as radiative molecule formation using high-level electronic structure calculations. We study the role of light-assisted processes and show that the efficiency of the dominant chemical pathways is considerably enhanced in excited reaction channels. Our results illustrate the importance of radiative and nonradiative processes for the cold chemistry occurring in ion-atom hybrid traps.

Theoretical investigation on photoionization from Rydberg states of lithium, sodium and potassium

Cross sections for s, p and d have been computed in the framework of a single-electron model (non-relativistic) by using a parametric central potential. The evolution of the non-hydrogenic behaviour of photoionization cross sections near threshold is studied along Rydberg series; non-hydrogenic characters are particularly large for all the ns series and for the np series of K. The validity of the method is discussed and it appears that sigma sigma np and sigma nd values are more reliable than sigma ns. The results are compared to experimental data and other theoretical results, mainly provided by the quantum-defect theory. The agreement between the various results is generally very good for sigma np and sigma nd; the agreement is satisfactory even for the most unfavourable cases provided by sigma ns of Na and K.

Calculations of transition and permanent dipole moments of heteronuclear alkali dimers NaK, NaRb and NaCs

Obtaining ultracold samples of dipolar molecules is a current challenge which requires an accurate knowledge of their electronic properties to guide the ongoing experiments. In this paper, we calculate permanent dipole moments and transition dipole moments for excited states for alkali dimers NaK, NaRb and NaCs using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective terms for core polarization effects. We provide an extensive set of data concerning transitions among the first seven molecular states of each symmetry 1Σ+, 3Σ+, 1Π, 3Π. The accuracy of our results is generally improved compared to previous similar calculations on NaK, while they are found to be in good agreement with the few NaRb states calculated with other methods. Results for NaCs transition dipole moments are given here for the first time.

Electronic structure of the magnesium hydride molecular ion

In this paper, using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective core polarization potentials, we investigate the electronic properties of the MgH

Reinvestigation of the Rb2 (2)Π3g−a Σ3u+ band on helium nanodroplets

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The electronic structure of the alkaline-earth-atom (Ca, Sr, Ba) hydride molecular ions

ion. We first determine potential energy curves for several states using different basis sets and discuss their predicted accuracy by comparing our values of the well depths and position with other available results. We then calculate permanent and transition dipole moments for several transitions. Finally for the first time, we calculate the static dipole polarizability of MgH

Structure of the alkali-metal-atom + strontium molecular ions: towards photoassociation and formation of cold molecular ions.

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Electronic properties of francium diatomic compounds and prospects for cold molecule formation

as function of the interatomic distance. This study represents the first step towards the modeling of collisions between trapped cold Mg