[en] The electronic transition moments of lowest electronic states of YF molecule have been investigated by using the electronic wave functions obtained from a previous ab initio (CASSCF and MRCI) calculation for the lowest 20 bound states in the representation ^2S+1Λ^(+/-) (neglecting spin-orbit effects) and 41 electronic states in the representation Ω^(+/-) (including spin-orbit effects). Based on a canonical functions approach for the determination of the vibrational wave functions the eigenvalues E_v, the rotational constants B_v, and abscissas of the corresponding turning points (R_min and R_max) have been investigated for all these states up to v = 23. The comparison of the present results with those available in the literature shows a very good agreement

[en] The electronic structure with spin–orbit effects of the yttrium nitride YN molecule are investigated by the methods of multireference single and double configuration interaction, including Davidson correction to account for quadruple excitations (MRSDCI + Q). Spin–orbit effects are taken into account via a semi-empirical pseudo-potential for the yttrium atom, while they have been neglected for nitrogen. The potential energy curves are calculated along with the spectroscopic constants for the lowest lying 38 spin–orbit states Ω in YN. A good agreement is displayed by comparing the calculated spectroscopic constants with those available experimentally. The permanent dipole moments are calculated along with the vibrational energies. We identify two vibrational energy levels in the spectra of the yttrium nitride molecule X¹∑⁺ (v = 0) → (1)¹∑⁺ (v′ = 0) that satisfy the criteria of laser cooling in molecules. New results are obtained in the present work for 32 spin orbit states and their spectroscopic constants calculated

[en] Graphical abstract: For the molecule YS the potential energy curves of 55 electronic states in the representation Ω^(±), including the spin–orbit (SO) effects, have been calculated along with the corresponding spectroscopic constants, the permanent dipole moments, the eigenvalues E_v, the rotational constants B_v, the centrifugal distortion constant D_v and the abscissa of the turning points r_min and r_max. Highlights: ► The potential energy curves of 55 electronic states have been investigated. ► Twenty-one new electronic states have been studied for the first time. ► Up to v = 28, E_v, B_v, D_v, r_min and r_max have been calculated. ► The energy T_e, the constants r_e, ω_e, and B_e are determined. - Abstract: An ab initio calculation (single and double excitation plus Davidson correction) have been performed for the molecule Yttrium monosulfide YS. The potential energy curves of 55 electronic states in the representation Ω^(±), including the spin–orbit (SO) effects, have been calculated along with the corresponding spectroscopic constants. The SO effects are taken into account via a semi-empirical pseudo-potential for yttrium atom, while they have been neglected for sulfur. A very good agreement is displayed by comparing the present results with those obtained experimentally for the two states ²Π_1/2 and ⁴Π_1/2. For the investigated electronic states without spin–orbit, the permanent dipole moments as a function of the internuclear distance, the eigenvalues E_v, the rotational constants B_v, the centrifugal distortion constant D_v and the abscissa of the turning points r_min and r_max have been investigated. New results have been obtained for 21 electronic states including their SO components