On the other hand, the (HS-LS) interaction energy difference becomes more significant as the Fe-O distance decreases (see Figure ). For instance, at very short Fe-O distances of 3.65 Å, the (HS-LS) interaction energy difference decreases by 0.043 eV and 1.556 eV for pose A and B, respectively. While previous BLYP-D3 ab initio MD simulations has shown that such distances are on the limit of being accessible by water molecules in solution at room temperature, the overall steepness of the repulsive wall becomes important for solutions where the solvent shell experiences pressure from the bulk solvent.