Analytic Potential Energy Function for Doubly Charged Ions HBe^(2+), HB^(2+), and HF^(2+)

It is well known that the potential curve of ground state for almost all neutral diatomic molecules has only one minimum.However,the doubly charged diatomic ions may have both potential minimum and maximum or singly repulsive branch.In order to describe the potential of this kind of diatomic ions,two of the authors Zhu and Wang have proposed a new analytical potential function with four parameters ai(i=l,...,4),andρ=R-R_(min) for those with both minimum and maximum,andρ=R for those with singly repulsive branch.The present work has derived this new potential function for HBe^(2+)with R_(min)=0.182 nm,R_(max)=0.335 nm andΔE=E_(max)-E_(min)=0.84 eV,and for HBe2+with R_(min)=0.147 nm,R_(max)=0.185 nm andΔE=E_(max)-E_(min)=0.062 eV.It is found that the potential for HF^(2+)is one with singly repulsive branch.The dissociation limits,parameters ai(i=1,...,4),force constants and spectroscopic data of these ions all are given out.