This video shows a simulation of an organic molecule steered toward, adsorbed to, and steered away from a phenolated and carboxylated sheet of graphene. The system size was approximately 50x50x60 Å following equilibration. Trajectories were computed using LAMMPS with the TIP3P water model and the OPLS-AA force field for the carbon sheets and organic molecule (PFOS anion, electrically balanced by a potassium ion not shown for clarity). The graphene oxide atoms were held in place by setting the force on each graphene oxide atom to zero at each time step. The system was equilibrated in the NPyT ensemble for 50 ps while allowing volume dilation in the y dimension, and subsequent dynamics were performed in the NVT ensemble at 298 K. The Colvars package was then used to apply -- to each atom in the PFOS molecule -- a harmonic potential centered at 6 Å in the z dimension (for 20 ps) and, following 20 ps of unbiased dynamics, a second harmonic potential centered at 25 Å (for another 20 ps). Unbiased trajectories were computed for a final 20 ps stretch such that the total simulation time was 130 ps. The simulation was visualized using OVITO.

DISCLAIMER: The structure and dynamics of the graphene oxide is inaccurate.

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