A systematic study of the collison dynamics associated with depopulation of Na(8s) atom colliding with ground state He has been made by applying the semi-classical impact parameter method using molecular orbital (MO) basis sets of different sizes. The cross-sections for total depopulation of the parent atom as well as those for individual transitions have been calculated. It is shown that the basis set must be large enough so as to include not only the immediate adjacent states coupling with the parent state but also other nearby states, which can affect the overall flux distribution in the reaction.
