We study the entanglement dynamics of T-C (Tavis-Cummings) model without rotating wave approximation. By using
displaced coherent state method, the influence of initial state and coupling strength to concurrence is numerically studied.
Our result demonstrates that the entanglement between two atoms always keep maximum when the initial state is antisymmetric
while the non-entangled initial state produce entanglement periodically due to the effect of non-rotating
terms. We also show that the coupling strength between the cavity field and atoms play a critical role in the entanglement