The ground state (X^1∑g^+) of beryllium dimer was investigated within the frozen-core approximation at the full CI level with the basis set containing bond functions (BFs). The role of the BFs in the calculation was examined in detail. In each case, the BSSE was also evaluated according to Boys and Bernardi. The improved results for the X^1∑g^+ of beryllium dimer show that the BFs method is a good alternative approach in the calculation of the molecules containing shallow potential well.

Key words: STABILITY, BERYLLIUM, FUNCTION