Treatment of electrostatic interactions in simulations of the interface between transition metal surfaces and organic matter: the discrete classical model and the reaction-field dielectric method

Abstract

A more efficient molecular dynamics model is devised to study the interface between platinum(111) and liquid isopropanol. The faster reaction-field dielectric method (RFD) is investigated as the alternative to the very accurate discrete classical model (DCM) (M. W. Finnis, Surf. Sci., 1991, 241, 61) to account for the electrostatic interactions at the interface. Differences in static and dynamic properties of the interface are examined. The mass-density and number-density distributions showed only a little sensitivity towards the choice of the method. The orientational structure revealed notable but still small quantitative changes for highly-polarized parts of the isopropanol molecules if the RFD is used instead of the DCM. The general qualitative picture is still preserved. The simulations of the platinum(111)/isopropanol interface with the DCM or the Ewald summation were carried out for longer times than in our previous contribution (K. B. Tarmyshov and F. Müller-Plathe, J. Chem. Phys., 2007, 126, 74702). The analysis disclosed that the influence of chemical or electrostatic interactions at the interface on the relative orientation of the neighbouring hydroxyl groups, which are adsorbed on the surface, is notably smaller than reported before. Overall, the reaction-field dielectric method can be used to study the properties of the interface between transition metals and organic matter, if there appears a chemical bond of 10 kT or higher between the surface and adsorbate molecules or their parts.

19F NMR Studies of 3M Ionomer Adsorption on Carbon Supports and Pt/C Catalysts

“…formation of CO2 or other volatile products. Similar adsorption phenomena have been reported and studied previously (23)(24)(25). The interaction between the metal surface and adsorbate molecules are identified as two types: physisorption and chemisorption.…”

“…In physisorption, the dynamics are driven by weak attractions between atoms and electrostatic interaction, whereas in chemisorption, the adsorption energy is significantly higher and may even cause distortion in the adsorbed molecule. In the case of alcohol adsorption onto the Pt surface, the adsorption mechanism is still under debate (23)(24)(25)(26). Our thermal study shows that the adsorbed molecules decompose above 100°C, which is above the 80°C fuel cell operation temperature.…”

The Interface Between Platinum(111) and Poly(vinyl Alcohol) Melt: A Molecular Dynamics Study

“…However, the distributions are qualitatively similar. Moreover, we have also compared the outcome of the reaction field dielectric method (RFD) to the results obtained using the discrete classical model (DCM) (29)(30)(31). There was a good agreement for the most structural properties of the interface mentioned before and the exchange dynamics.…”