Correlated configuration interaction investigation on low-lying states and optical transition of gold boron

Abstract

High-level configuration interaction method including the spin-orbit coupling is performed to investigate the low-lying electronic states of AuB that is not reported by the experiment. The electronic structure in our work is preformed through the three steps stated below. First of all, Hartree-Fock method is performed to compute the singlet-configuration wavefunction as the initial guess. Next, we generate a multi-reference wavefunction by means of state-averaged complete active space self-consistent field (SACASSCF). The last, the wavefunctions from CASSCF are utilized as reference, the exact energy point values are calculated by the explicitly dynamic correlated multi-reference configuration interaction method (MRCI). The Davidson correction (+Q) is put forward to surmount the size-consistence problem caused by the MRCI method. The spin-orbit effect and correlation for inner shell and valence shell electrons are considered into our calculation to make a guarantee of accuracy. The potential energy curves of 12 Λ-S electronic states are obtained. Depended the explicit potential energy curves, we calculate the spectroscopic constants through solving radial Schrödinger equation numerically. We analysis the influence of electronic state configuration on the dipole moment with the help of the variation of dipole moment as the function of nuclear distance. The spin-orbit matrix elements for parts of low-lying states are computed, and the relation of spin-orbit coupling and predissociation are discussed. The predissociation is analyzed with the help of the obtained spin-orbit matrix elements of the 4 Λ-S states which spilt into 12 Ω states. It indicates that due to absence of the intersections between the curves of spin-orbit matrix elements related with the 4 low-lying Λ-S states, the predissociation for these low-lying states will not occur. Finally, the properties of optical transition between the ground Ω state <i>A</i>¹∏₁ and first excited Ω state <i>X</i>¹∑_0⁺ are discussed in laser-cooling filed by analyzing the Franck-Condon factors and radiative lifetime. And the transition dipole moment is also calculated. But our results reveal that the AuB is not an ideal candidate for laser-cooling. In conclusion, this work is helpful to deepen the understanding of AuB, especially in structures of electronic states, interaction between excited states and optical transition properties.