Study On Spectral Properties Of OH Molecules By MRCI Theory

In this paper, the potential curves for the ground state and excited state of OH molecule were calculated by using multi-reference configuration interaction approach in different levels of basis set. Based on the PECS, the radial Schrodinger equations of nuclear motion were numerically treated by Level program, vibrational levels and rotational constants were deduced for various electronic states, then the obtained spectroscopic date of various electronic states are found significant after comparing with the experimental values.This paper is divided into five parts. In the first part, we will present the significance and research status of molecular spectroscopy and potential energy functions. In the second part, we introduce the theoretical research of atoms and molecules. In the third part, we introduce the theory and calculation methods of the quantum mechanical calculation. In the fourth part, the six doublet and two quartet electronic states(2?????,2??,2????,2?,4??,and?4?) of OH radical have been studied with multi-reference configuration interaction(MRCI) method where the Davidson correction, core-valence interaction and relativistic effect are considered with large basis sets aug-cc-pv5 z, aug-cc-pcv5 z, and cc-pv5z-DK, respectively. Potential energy curves(PECs) and dipole moment functions are calculated for these states where the nuclear distance changing from 0.05 nm to 0.80 nm. All possible vibrational levels and rotational constants for the bound state X2? and A2?+ of OH are predicted by numerical solving the radial Schr?dinger equation through the Level program, and spectroscopic parameters are obtained which are in good agreements with experimental results. Transition dipole moments between the ground state X2? and other excited states are also computed with MRCI and the transition probability, lifetime as long as Franck-Condon factors for the A2?+-X2? transition are discussed and compared with existing experimental values. In the last section, we summary the final results of the research work.The calculated of the potential curves and vibrational levels and rotational constants of OH molecule in this paper can provide reference for pepole to research of OH molecule in the future.