Regarding neutral trivalent methylarsenicals, the adsorption energy is strongly determined by the magnitude of intermolecular electrostatic interactions, with an EELEC contribution of up to 61% (Fig. ). Note that EELEC in aqueous solution also tracks the energy penalty due to the solvation process because Coulomb potential V is inversely proportional to the solvent dielectric constant (); in other words, EELEC contains the contribution from solvation energies. With this in mind, electrostatic interactions are a key stabilizing driving force even in aqueous environments. Despite the latter, the charge-transfer term (ECT) displays the second-highest contribution (up to 38%), in agreement with the relative high magnitude of electron transfer between methylarsenicals and phosphorene oxide (pollutants transfer 0.2-0.4 electrons after uptake, indicating its donor character or pollutant → PhosO electron transfer). Thus, the key stabilization gained by ECT contribution is related to the charge-flow between fragments upon adsorption, i.e., increasing the number of methyl groups increases in methylarsenicals. In addition, the larger magnitude of ECT term in the case of PhosO-DMA III and PhosO-TMA III complexes explain their relatively higher adsorption energies than the MMA III adsorption, mainly because ECT term show dependence on orbital interactions, relative orientation, and separation between molecular fragments. Therefore, the arsenic atom of DMA III and TMA III must be influenced by the substrate at shorter intermolecular distances. As an illustration, the PhosO-MMA III complex (dPhosO-As3.9 Å) shows a higher ECT=-0.79 eV than PhosO-DMA III complex (dPhosO-As2.6