Energy dependence for directed and elliptic flow in in termediate-energy heavy ion collisions

Differential and integrated directed flow and elliptic flow of light charged particles (z ≤ 2) are studied systematically for semi-central (b = 5 fm) ¹⁹⁷Au+¹⁹⁷Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between mean field and nucleon-nucleon collisions and also between collective rotation and expansion.