Assuming each PIBSI molecule displaces one iso-octane molecule, the energy change based on the DFT calculations of TEPA and iso-octane adsorption will be -7.4 kcal mol -1 , which agrees well with the adsorption enthalpy from the MD simulations (-6.0 kcal mol -1 ) in Figure . For the zwitterionic surfactant, assuming that two iso-octane molecules are displaced due to the larger head-group size, the energy change based on the DFT calculations of TMA and iso-octane adsorption will be -17.7 kcal mol -1 , which is in also reasonable agreement with the adsorption enthalpy from the MD simulations (-16.0 kcal mol -1 ), see Figure . Therefore, the DFT calculations are in solid quantitative agreement with the MD simulations for the deposit-DCA systems under study.