In this talk, Zhenyu Wei first introduced the obstacles in simulating large bio-systems and the current solutions, which are, in this talk, categorized into enhanced sampling and coarse-grained modeling. Then Zhenyu Wei introduced the base idea of the implicit solvent model with the deduction of the General Born model. In the final, Zhenyu Wei shows the result of peptide interaction, which is computed by enhanced sampling method and utilized as the fundamental of OpenPD.