TEST OF THE VALIDITY OF THE DENSITY-MATRIX EXPANSION METHOD FOR ION-ION COLLISION PROCESS

In the present work, we test the validity of replacing the nondiagonal densities rho((r) over right arrow, (r) over right arrow') appearing in the exchange part of the nucleus-nucleus optical potential by an ap proximation based on the density matrix expansion (DME) used frequentl y in nuclear structure calculations. This procedure has been used rece ntly by many authors in driving the real nucleus-nucleus potential. We have found that for M3Y-Paris nucleon-nucleon interaction the use of DME may produce a maximum error of 12% in the nucleus-nucleus potentia l.