Using the density functional B3P86/cc-PV5Z method, the geometric structure of BH molecule under different external electric fields is optimized, and the bond lengths, dipole moments, vibration frequencies, and other physical properties parameters are obtained. On the basis of setting appropriate parameters, scanning single point energies are obtained by the same method and the potential energy curves under different external fields are also obtained. These results show that the physical property parameters and potential energy curves may change with external electric field, especially in the case of reverse direction electric field. The potential energy function without external electric field is fitted by Morse potential, and the fitting parameters are obtained which are in good agreement with experimental values. In order to obtain the critical dissociation electric parameter, the dipole approximation is adopted to construct a potential model fitting the corresponding potential energy curve of the external electric field. It is found that the fitted critical dissociation electric parameter is consistent with numerical calculation, so that the constructed model is reliable and accurate. These results will provide important theoretical and experimental reference for further studying the molecular spectrum, dynamics, and molecular cooling with Stark effect.
High level calculations on the ground state of12Mg1 H molecule have been performed using multi-reference configuration interaction(MRCI) method with the Davidson modification. The core–valence correlation and scalar relativistic corrections are included into the present calculations at the same time. The potential energy curve(PEC) of the ground state, all of the vibrational levels and spectroscopic parameters are fitted. The results show that the levels and spectroscopic parameters are in good agreement with the available experimental data. The analytical potential energy function(APEF) is also deduced from the calculated PEC using the Murrell–Sorbie(M–S) potential function. The present results can provide a helpful reference for the future spectroscopic experiments or dynamical calculations of the molecule.
The potential energy curves(PECs) of 14 Λ–S states for magnesium chloride(Mg Cl) have been calculated by using multi-reference configuration interaction method with Davidson correction(MRCI + Q). The core-valence correlation(CV), scalar relativistic effect, and spin–orbit coupling(SOC) effect are considered in the electronic structure computations.The spectroscopic constants of X^2Σ^+ and A ~2Π states have been obtained, which are in good agreement with the existing theoretical and experimental results. Furthermore, other higher electronic states are also characterized. The permanent dipole moments(PDMs) of Λ–S states and the spinorbit(SO) matrix elements between Λ–S states are also computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the avoided crossing between the states with the same symmetry. The SOC effect is taken into account with Breit–Pauli operator, which makes the 14Λ–S states split into 30 ? states, and leads to a double-well potential of the ? =(3)1/2 state. The energy splitting for the A2Π is calculated to be 53.61 cm^(-1) and in good agreement with the experimental result 54.47 cm^(-1). The transition dipole moments(TDMs), Franck–Condon factors(FCFs), and the corresponding radiative lifetimes of the selected transitions from excited ? states to the ground state X^2Σ + 1/2 have been reported. The computed radiative lifetimes τν of low-lying excites ? states are all on the order of 10 ns. Finally, the feasibility of laser cooling of Mg Cl molecule has been analyzed.
