Spectroscopic Properties Investigations Of Low-lying Electronic States On Diatomic Molecules

As the foundation of atomic and molecular reaction dynamics and collision, the molecular potential energy function is very important,which can describe the properties of molecular completely, including the spectroscopic properties, molecular energy and mechanical properties. In the atomic and molecular discipline, molecular potential energy curves and the analytic formula are one of the most important research direction. In present paper, the molecular potential energy function of PCI and BP radicals was reported, including the potential energy curves, spectroscopic constants, transition properties and the effect of corrections on spectroscopic properties, and further expand the spectroscopic information of the two radicals.In this paper, the PC1 was firstly studied, the 19 A-S states and correspond potential energy curves were taken into consideration. The 33∑-,13∑+,13△,23A and 15Π states are the repulsive states; The 11∑-21△ and 15∑- states and the second well of A3Π state are very weakly-bound ones; Among the Π states, the A3Π and B3Π, B3Π and C3Π,21Π and 31Π have the avoided crossings; The transition from A3Π, B3Π, C3Π to X3∑-, and c1Π,31Π,21Π to a1△ were also calculated for several low vibrational states including the Frank-Condon factors and radiative lifetimes. Secondly, the 20 A-S states of BP were calculated, which were yielded from the first two dissociation limits. All of the 20 A-S states are bound states, internuclear separations from about 0.14 to 0.68 nm were calculated. The 23∑- and 33∑- states have the avoided crossings, which are very weakly-bound ones. The 21∑-,13A and 23A states possess the double well. Subsequently, the transition dipole moments, the Franck-Condon factors and the radiative times of the transitions 31Π-b1Π,23△-X3Π,23∑--A3∑-,33∑--A3∑- and 15∑--15Π are calculated.During the calculations, the potential energy curves were calculated by the complete active space self-consistent field method (CASSCF), which is followed by the internally contracted multireference configuration interaction approach (icMRCI) with the Davidson correction with the MOLPRO 2010.1 program package.Secondly, PECs are also extrapolated to the complete basis set limit. The core-valence correlation and scalar relativistic corrections are included into the present work. At the same time, the convergent behavior of present calculations is discussed with respect to the basis set and level of theory. The transition dipole moments, the Franck-Condon factors and the radiative times of the transition properties were calculated with the LEVEL Program. In this paper the calculations results were also compared with the available measurements and other theoretical results.In summary, by analyzing the calculation results, we found that the corrections have obvious effect on spectroscopic constants, though the effect of these corrections is different, they were important to improve the accuracy of spectroscopic constants. In present work, the accuracy of spectroscopic constants were also improved after considering all kinds of corrections. By analyzing the transitions properties, we can further understand the spectroscopic properties. The transitions properties of double atomic molecular can also provide references for future experimental or theoretical research.