2017. 58, 1 – UDC 541.6:546.32:546.291 ELECTRONIC STRUCTURE WITH A DIPOLE MOMENT CALCULATION OF THE LOW-LYING ELECTRONIC STATES OF THE KHe MOLECULE S. Kontar, M. Korek Faculty of Science, Beirut Arab University, Beirut, Lebanon E-mail: fkorek@yahoo.com; Mahmoud.korek@bau.edu.lb Received June, 30, 2015 The KHe molecular system is extensively studied by multi-reference configuration interaction calculations. <...> Potential energy curves are constructed for 20 lowest electronic states, and molecular parameters are extracted. <...> A comparison of our results with previous works shows remarkable agreement. <...> A further calculation of the dipole moment functions through a wide range of the internuclear separation is performed and their corresponding curves are presented. <...> Charge transfer is detected from the change in the sign of these functions particularly for R < Re. <...> On the other hand, weakly binding long-range excited states predict positive values of the dipole moment near Re reflecting the K–He+ polarity. <...> DOI: 10.15372/JSC20170104 Keywords: ab initio calculation, KHe molecule, potential energy curves, spectroscopic constants, dipole moment. <...> In the investigation of the unique properties of such molecules, alkali metals are among the best candidates due to their simple electronic configuration and the presence of optically accessible electron transitions. <...> Moreover, alkali metals are particularly important in helium nanodroplet isolation spectroscopy [ 1, 2 ] because they reside on the surface of superfluid He droplets whereas most other atoms or molecules move to the center. <...> The experimental emission spectra of alkali metal-helium exciplexes were reported [ 3, 4 ]. <...> Also, the exploration of the photoabsorption spectra of alkali metal-rare gas systems and the location of possible satellite peaks constitute strong tools for understanding the atmospheres of brown dwarfs and other astrophysical objects, such as extrasolar giant planets dominated by alkali-metal atoms [ 5—8]. <...> These compounds are also considered to play a major role in exciplex laser field due to their repulsive ground state and a comparatively more stable first excited state [ 9—12]. <...> Their potential as exciplex lasers has theoretically been confirmed for both diatomic and triatomic systems [13—15 ]. <...> The work presented here uses an ab initio <...>