MRCI Calculations Of The Ground And Excited Sates For HF Molecule And HF~+Ion

Potential energy function （PEF） and spectroscopic properties of HF molecule andHF⁺ion is alwaye one of the important research directions in molecular physics.Potential energy curves （PECs） for the singlet and triplet low-lying electronic excitedstates of HF molecule have been calculated using the multi-reference configurationinteraction （MRCI） method with the basis set of aug-cc-pVTZ where the Davidsoncorrection was considered as approximation to full CI. The characteristics of thesePECs are discussed by considering the group theory and molecular dissociation limits,and the ionic nature of the B¹Σ+state is proved where the PEC tends to the H⁺+F^-(¹S)dissociation limit. Based on these PECs, the PECs of ground state and electronicexcited states for HF molecule were fitted to the Murrell-Sorbie（MS） potentialfunction, then use the fitting parameters to calculate the quardratic, cubic and quarticforce constants, and further some spectroscopic datas as harmonic vibrationalfrequency ω_e, the inharmonic vibrational factorω_eχe, the rigid-rotational factor B_eandthe nonrigid-rotational factor aecan be determined for each electronic state. And thenthe radial Schr dinger equations of nuclear motion are resolved and the vibrationallevels and rotational constants for X¹Σ⁺, B¹Σ+,C1Π and D¹Σ⁺states were obtainedwhen the rotational quantum number J equals zero （J=0）. Then the spectroscopicconstants for these states were determined through spectral fitting method, all thecalculation results are in good agreement with the experimental values.We study HF⁺ion by MRCI+Q method with the basis sets ofaug-cc-PVnZ（n=T,Q） and obtain potential energy curves for the doublet low-lyingelectronic excited states of HF⁺ion. The ground state X²Π and first excited stateA²Σ⁺can be determined. Like HF molecule, the PECs of ground state and electronicexcited states of HF⁺ion were fitted to the Murrell-Sorbie potential function, then usethe fitting parameters to calculate the quardratic, cubic and quartic force constants,and further some spectroscopic data as harmonic vibrational frequency ω_e, theinharmonic vibrational factorω_eχe, the rigid-rotational factor B_e and thenonrigid-rotational factor aecan be determined for each electronic state. And then theradial Schr dinger equations of nuclear motion are resolved and the vibrational levelsand rotational constants for X²Π and A²Σ⁺states were obtained when the rotationalquantum number J equals zero （J=0）. Then the spectroscopic constants for these stateswere determined through spectral fitting method, all the calculation results are in goodagreement with the experimental values. So far the main works focus on the ground states for HF molecule and HF⁺ion,and the research for the other states is not very satisfactory. The study can more fullyunderstand the structure and characteristic of the HF molecule and HF⁺ion. Ourpresent researches can provide beneficial reference for further experimental andtheoretical studies of the HF molecule and HF⁺ion.