MRCI study on electronic spectrum of several low-lying electronic states of the SiO+ cation

► Effects on the spectroscopic parameters by the SO coupling are discussed. ► Core-valence correlation and relativistic corrections are included in the calculations. ► Effect on the spectroscopic parameters by the nonadiabatic correction is very small. ► Results calculated by the MRCI + Q/AV6Z + CV + DK achieve much high accuracy. ► Spectroscopic parameters of splitting electronic states are determined.