The preparation of switchable azobenzene derivatives driven by visible light is desirable for applications in biomolecular systems. o-R-substituted 4,4'-diacetamidoazobenzene derivatives (R=H, CH3, OCH3 or OH) were investigated by using both density functional theory (DFT) and reactive molecular dynamics simulations. DFT calculations demonstrated that the nonplanar azo trans geometric structure, which caused by bulky groups tetra substituted in the ortho-position, is the key factor to enable the trans cis transition with visible light. Furthermore, 100 independent reactive MD simulations demonstrated that 71% trans isomers of tetra o-OCH3-substituted 4,4'-diacetamidoazobenzene translated to cis, in good agreement with the experimental data. (C) 2014 Elsevier B.V. All rights reserved.