Isovector dipole resonances in the oxygen isotopes18∼24Oand fusion reactions of16O+16Oare studied using an extended version of the time-dependent Hartree-Fock theory known as the time-dependent density-matrix theory (TDDM). A newly developed TDDM program which includes spin-orbit force in a mean-field potential is used. Low-lying dipole strength in the oxygen isotopes is compared with experimental data and also with a shell-model calculation. It is found that the observed isotope dependence of low-lying dipole strength is reproduced in TDDM when the strength of the residual interaction is appropriately chosen. For the fusion reactions, it is found that the dissipation of translational energy due to two-body collisions is small when spin-orbit force is included in the mean-field potential. ©2001 American Institute of Physics.