Electronic Structure and Dipole Moment Calculations of the Electronic States of the Molecule BeCl

Boushra El Rafei,Ghassan Younes,Mahmoud Korek,Sahar Kontar

doi:10.5539/mas.v11n6p90

Abstract

The electronic structure of the molecule BeCl have been investigated by using the Complete Active Space Self Consistent Field (CASSCF) with Multireference Configuration Interaction MRCI+Q (singly and doubly excitation with Davidson corrections). The potential energy curves, in terms of the internuclear distance R, have been calculated for 13 doublet and 14 quartet electronic states in the representation 2s+1Λ(+/-) of the molecule BeCl. The internuclear distance at equilibrium Re, the electronic energy with respect to the ground state Te, the harmonic frequency we, the rotational constants Be and the permanent dipole moment have been calculated for the bound electronic states. The Franck-Condon factor is calculated for the electronic transition between the two electronic states X2S+-(1)2P. Since there is limited data are published in literature, twenty-two new electronic states have been investigated here for the first time for the molecule BeCl. The comparison between our calculated values and those available in the literature shows a very good good agreement.

Highlights

The alkaline-earth monohalide received a considerable attention from experimentalists since the early thirties (Fredrickson and Hogan Jr 1934)
While the Franck–Condon factors (FCFs) calculation is based on the accurate potential energy curve of two electronic states, the radiative lifetimes needs the calculation of the dipole moment
In order to provide an accurate global picture of a manifold of electronic states of BeCl molecule and quantitatively account of the observed spectra we present in this work, the theoretical electronic structure of BeCl molecule

Summary

Introduction

The alkaline-earth monohalide received a considerable attention from experimentalists since the early thirties (Fredrickson and Hogan Jr 1934). Shuman et al (Shuman, Barry, & DeMille 2010) introduce the first direct cooling of a polar molecule (SrF) by using an optical cycling scheme with Doppler and Sisyphus cooling forces This significant innovation needs a deep knowledge of the electronic structure and its ro-vibrational energy levels of the ultracold candidate molecule. While the FCF calculation is based on the accurate potential energy curve of two electronic states, the radiative lifetimes needs the calculation of the dipole moment. DeMille (DeMille2002) has detailed a prototype design for quantum computation using ultracold polar molecules, trapped in a one-dimensional optical lattice, partially oriented in an external electric field, and coupled by the dipole-dipole interaction This offers a promising platform for quantum computing because scale-up appears feasible to obtain large networks of coupled qubits. The Franck-Condon factors have been calculated for electronic transitions with the discussion on the feasibility of laser cooling of the BeCl molecule

Method

Potential Energy Curves and Spectroscopic Constants

Franck-Condon Factor

Conclusion