  The mechanism of multinucleon transfer (MNT) reactions for producing
neutron-rich heavy nuclei around N = 126 is investigated within two different
theoretical frameworks: dinuclear system (DNS) model and isospin-dependent
quantum molecular dynamics (IQMD) model. The effects of mass asymmetry
relaxation, N=Z equilibration, and shell closures on production cross sections
of neutron-rich heavy nuclei are investigated. For the first time, the
advantages for producing neutron-rich heavy nuclei around N = 126 is found in
MNT reactions based on 238U target. We propose the reactions with 238U target
for producing unknown neutron-rich heavy nuclei around N = 126 in the future.
