We performed fully atomistic molecular dynamics(MD) simulations for para-tolyl-BTBT-C₁₀, asymmetric liquid crystalline organic semiconductor, to reveal the mechanism of molecular inversion and molecular diffusion around the phase transition temperatures. From the results of MD simulation, we obtained the crystal/smectic E(SmE)/smectic B(SmB) transitions. And at the SmE/SmB transition temperature, we observed molecular inversion dynamics, in which molecules first lie between molecular layers and then reenter the original or forward/backward layer.