MRCI Investigation On Spectroscopic Properties For Electronic States Of BeH And BeH~+

Multiconfiguration self-consistent field and multiconfiguration reference interaction (MRCI)including the Davidson’s correction techniques were employed to calculate the low-lying statesof the BeH and BeH+electronic states. The potential curves for the ground state and excitedstate were determined. Based on the PECs, the radial Schr dinger equations of nuclear motionwere numerically treated and vibrational levels were deduced for bound states. Then theobtained spectroscopic data are found significant after comparing with the experimental values.In this paper, it is organized as follows. In the next section we will present the purpose andsignificance of studying the spectra of diatomic molecules. The second part, we introduce theresearch progress of the vibrational levels of diatomic molecules, as well as the main methodAfterwards some quantum mechanical calculation methods will be instructed. In last sectionpotential energy curves(PECs) for the ground state and the excited electronic states of BeH andBeH+molecule are calculated using the multi-configuration reference single and double excitedconfiguration interaction (MRCI) approach in combination with the aug-cc-pVTZ basis sets.With the potential, all of the vibrational levels and inertial rotation constants are predicted whenthe rotational quantum number J is set to equal zero (J=0) by numerically solving the radialSchr dinger equation of nuclear motion. Then the spectroscopic data is obtained respectivelyincluding the rotation coupling constant ωe, the anharmonic constant ωexe, the equilibriumrotation constant Beand the vibration-rotation coupling constant αe.In summary, this study reports a global view of the potential energy curves, vibrationalenergy levels and spectroscopic constants for low-lying states. Based on the potential obtainedemploying the MRCI method, all of the vibrational states and the spectroscopic constants arepredicted. It shows that the present spectroscopic constants are in excellent agreement with theavailable experimental values and more accurate as a whole when compared with the previoustheoretical investigations. And our work can provide reference for experiment and performdynamic calculations in the future.