Simulation of ion behavior in an open three-dimensional Paul trap using a power series method

Simulations of the dynamics of ions trapped in a Paul trap with terms in the potential up to the order 10 have been carried out. The power series method is used to solve numerically the equations of motion of the ions. The stability diagram has been studied and the buffer gas cooling has been implemented by a Monte Carlo method. The dipole excitation was also included. The method has been applied to an existing trap and it has shown good agreement with the experimental results and previous simulations using other methods

Intermolecular interactions and stability of cationic alkali-dimers in He clusters

Satellite of ICPEAC 2019, Paris (France), July 20-22, 201

Nonradiative lifetimes for LiH in the a state using adiabatic and diabatic schemes

Accurate positions and nonradiative lifetimes of states belonging to the adiabatic A state of LiH are estimated. The results coming from a Golden Rule treatment in the adiabatic scheme present excellent agreement with those obtained through a diabatic close coupling calculation. That confirms the accuracy reached in both approaches and also in the treatment of the diabatic-adiabatic transformation. It involves, in particular, an effective phase control that is needed to properly estimate nonadiabatic couplings. Also, a powerful numerical procedure to obtain energy profiles in the diabatic close coupling frame is described and applied in this work. © 1997 American Institute of Physics.Action Integré Franco-Espagnole n0 96022 for support which has allowed this collaboration.Peer Reviewe

Modelling interactions of alkali-cation dimers in He clusters

1 pag., 1 fig.Doped He droplets constitute an important environment as ultracold homogeneous matrices for spectroscopic studies. Alkali metal dopants have a series of interesting properties due to their unusual bonding behavior. Neutral atoms attached to the surface of the droplet, forming eventually cold molecules via collisions, while charged dopants form solvation shells, related with the low mobility of the ions in experiments. So, investigations on the underlying intermolecular, markedly orientational ionic, forces, and on the miscoscopic structures of alkali-cation-He complexes is essential

Electronic Structure and Spectra of the MgLi⁺ Ionic Molecule

Using an <i>ab initio</i> approach based on nonempirical pseudopotentials for the Mg²⁺ and Li⁺ cores, Gaussian basis sets, effective core polarization potentials and full configuration interaction calculations, the adiabatic potential energy curves, the spectroscopic constants, the permanent and transition electric dipole moments of the several lowest electronic states of the alkali–alkaline earth ion MgLi⁺ have been performed. These states dissociate into Mg⁺(3s and 3p) + Li (2s, 2p, 3s, 3p, 3d, 4s, 4p, and 4d) and Mg (3s², 3s3p, 3s4s, 3s3d, 3s4p, 3s5s, and 3s4d) + Li⁺. The spectroscopic constants (<i>R</i>_e, <i>D</i>_e, <i>T</i>_e, ω_e, ω_e<i>x</i>_e, and <i>B</i>_e) of the ground state and nearly 53 excited states of ^1,3Σ⁺, ^1,3Π, and ^1,3Δ symmetries are derived. Most of them are computed for the first time. Moreover, several avoided crossings between the electronic states of ^1,3Σ⁺, ^1,3Π symmetries are localized and analyzed. Their existence is related to the interaction between the potential energy curves and to the charge transfer process between the two ionic systems Mg⁺Li and MgLi⁺. Furthermore, accurate adiabatic permanent and transition dipole moments for several transitions have been calculated for a large and dense grid of internuclear distances for the first 15 ¹Σ⁺ electronic states. A linear behavior is observed in the permanent dipole moments for several electronic states. Additionally, the transition electric dipole moments between neighbor states have shown many peaks situated around the avoided crossing positions

Theoretical Study of Cationic Alkali Dimers Interacting with He: Li2 +-He and Na2 +-He van der Waals Complexes

8 pags., 5 figs., 3 tabs. -- Published as part of The Journal of Physical Chemistry virtual special issue “F. Javier Aoiz Festschrift”.We present a theoretical study on the potential energy surface and bound states of He-A2+ complexes, where A is one of the alkali Li or Na atoms. The intermolecular interactions were systematically investigated by high-level ab initio electronic structure computations, and the corresponding raw data were then employed to reproduce accurate analytical expressions of the potential surfaces. In turn, we used these potentials to evaluate bound configurations of the trimers from nuclear quantum calculations and to extract information on the effect of orientational anisotropy of the forces and the interplay between repulsive and attractive interaction within the potential surfaces. The spatial features of the bound states are analyzed and discussed in detail. We found that both systems are going under large amplitude stretching and bending motions with high zero-point energies. Despite the large differences in the potential well-depths, the correct treatment of nuclear quantum effects provides insights on the effect of different strength of the ionic interaction on the spectral structure of such cationic alkali van der Waals complexes, related to the mobility of ions and the formation of cold-molecules in He-controlled environments.The authors thank the Centro de Calculo del IFF, SGAI (CSIC), and CESGA for allocation of computer time. This work has been supported by MINECO Grant Nos. FIS2014-51933-P and FIS2017-83157-P. N.A. and H.B. are grateful to the School of Research and Graduate Studies at the American University of Ras Al Khaimah for the financial support under Grant Number AAS/003/18. N.A. acknowledges financial support from from the Ministry of Higher Education and Scientific Research of Tunisia

Ab initio calculations of electronic structure of the BaCs molecule: adiabatic potential energy curves, spectroscopic constants, spin–orbit effect and permanent and transition electric dipole moments

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Computed distributions of rotovibrational transitions in

Accurate potential energy curves for the ground electronic states of LiH and $\rm LiH^{+}$ are employed to generate vibrational and rotational levels over a broad range of J values for both systems. The corresponding dipole functions are computed and used to obtain the frequency and intensity distributions of all relevant transitions between bound states for pure vibrational excitations, pure rotational excitations and for dipole allowed rovibrational processes. This extensive set of absorption data for both molecules is employed to locate the most likely region in the infrared spectrum where characteristic lines could be observed. Such data should be useful in experimental attempts to search for LiH and $\rm LiH^{+}$ lines at high redshifts. We found that transitions between ionic levels will be markedly less intense than those for the neutral system and that transitions between rotationally `hot' levels will be markedly more intense than those between low-J levels