A theoretical study of the accurate analytic potential energy curve and spectroscopic properties for AlF (X1Σ+)

In this paper, the energy, equilibrium geometry and harmonic frequency of the ground electronic state X1Σ+ of AlF have been calculated utilizing two quantum chemical methods (CCSD(T) and QCISD(T)) with four different basis sets (cc-pVQZ, cc-pV5Z, 6-311+G(3df) and 6-311G(3df)). Comparing various computational results mentioned above with the experimental values, it can be concluded that reliable equilibrium geometry calculations can be obtained at CCSD(T)/cc-pVQZ computational level of AlF (X1Σ+) molecule. The whole potential curves for the ground electronic state are further scanned using the CCSD(T)/cc-pVQZ method. The potential energy functions and relevant spectroscopic constants of this state are then obtained by least square fitting to the Murrell-Sorbie function and the modified Murrell-Sorbie+c6 function, respectively. It is shown that the Murrell-Sorbie function and the modified Murrell-Sorbie function are both very suitable for reproducing the accurate PEC of AlF (X1Σ+). Besides, our calculations are also more accurate than other theoretical results.