Investigation of Spectroscopic Properties and Spin-Orbit Splitting in the X2Π and A2Π Electronic States of the SO+ Cation

摘要

The potential energy curves (PECs) of the X²Π and A²Π electronic states of the SO⁺ ion are calculated using the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction (MRCI) approach for internuclear separations from 0.08 to 1.06 nm. The spin-orbit coupling effect on the spectroscopic parameters is included using the Breit-Pauli operator. To improve the quality of PECs and spin-orbit coupling constant (A0), core-valence correlation and scalar relativistic corrections are included. To obtain more reliable results, the PECs obtained by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). At the MRCI+Q/aug-cc-pV5Z+CV+DK level, the A0 values of the SO⁺(X²Π1/2, 3/2) and SO⁺(A²Π1/2, 3/2) are 362.13 and 58.16 cm⁻¹ when the aug-cc-pCVTZ basis set is used to calculate the spin-orbit coupling splitting, and the A0 of the SO⁺(X²Π1/2, 3/2) and SO⁺(A²Π1/2, 3/2) are 344.36 and 52.90 cm⁻¹ when the aug-cc-pVTZ basis set is used to calculate the spin-orbit coupling splitting. The conclusion is drawn that the core-valence correlations correction makes the A0 slightly larger. The spectroscopic results are obtained and compared with those reported in the literature. Excellent agreement exists between the present results and the measurements. The vibrational manifolds are calculated, and those of the first 30 vibrational states are reported for the J = 0 case. Comparison with the measurements shows that the present vibrational manifolds are both reliable and accurate.