Molecular hyperfine parameters in the 1 3Σu+ and 1 3Σg+ states of Li2, Na2, K2 and Rb2

Magnetic hyperfine parameters have been computed for the 1 3Σu+ and 1 3Σg+ states of Li2,Na2,K2 and Rb2. The parameters were computed with MCSCF wavefunctions and the calculations were repeated for a series of internuclear distances. The results are compared with a recent observation of the hyperfine structure in Rb2, and to the atomic hyperfine parameters. The available empirical data are reproduced with high accuracy. For the present systems, the molecular hyperfine parameters are largely determined by the corresponding atomic hyperfine interactions. The computed molecular parameters at the dissociation limit deviate at most 11% from the experimentally determined atomic ones.