The report by Skoulidas et al. seems to predict that only the outermost layer will ever retain CO 2 gas while the remainder of the pore interior is essentially vacant, since when pressures are increased to somewhere between 1 and 10 bar, the particles begin to scatter to the entire inner region of the pore. However, from the net density level as a function of radius, it can be seen that there is some influence on the gas due to an inner secondary layer and multiple gaseous layers have been reported by other workers who performed MD simulations on carbon nanotubes . Eq. ( ) can be used to estimate the nature of the potential well that generates a secondary layer if appropriate adjustments are made. First, we get a rough approximation for the number of CO 2 molecules in the outer layer, per particular volume, by using the ideal gas law to determine moles CO 2 in the volume V . We define V to be