Monte Carlo simulations of the adsorption of CO2 on the MgO(100) surface

Abstract

The adsorption of CO2 gas on the MgO (100) crystal surface is investigated using grand canonical Monte Carlo simulations. This allows us to obtain adsorption isotherms that can be compared with experiment, as well as to explore the possible formation of monolayers of different densities. Our model calculations agree reasonably well with the available experimental results. We find a "low-density" adsorbed monolayer where each CO2 molecule is bound to two Mg2+ ions on the MgO substrate. We also observe the formation of monolayers of higher density, where some of the CO2 molecules have rotated and tilted to expose additional binding sites. Low-temperature simulations of both the low- and high-density monolayers reveal that these states are very close in energy, with binding energies of approximately 7 kcal/mol at T=5 K. The high-density monolayer given by our model has a density that is significantly less than the reported experimental value. We discuss this discrepancy and offer suggestions for resolving it.

A Monte Carlo simulation study of H2 layers on NaCl(001)

“…In particular, the simulations show that a (1 Â 1) bi-layer structure is possible below 8 K (the temperature region of the Ewing's work) while above 12 K a (1 Â 1) monolayer structure will remain which is consistent with Heidberg's results. The regime between 8 and 12 K may be pressure dependent so that a complete resolution might require Grand Canonical MC simulation methods [16]. Finally, our PT calculations indicate that the choice of adsorption sites depends on the rotational states of hydrogen molecule, in particular; o-H 2 in state (J, jmj = AEJ) prefers to locate above the cationic site, whereas o-H 2 in state (J, jmj = 0) prefers to reside at the top of the anionic site.…”

Adsorption of H2O2 at the surface of Ih ice, as seen from grand canonical Monte Carlo simulations

“…Thus, by systematically varying the adsorbate chemical potential in a set of simulations the adsorption isotherm, i.e., the number of adsorbed molecules per surface unit as a function of the chemical potential, can be calculated. The GCMC method has successfully been applied to calculate the adsorption isotherm in a wide variety of such systems [6][7][8][9]13,14,[17][18][19][20][21][22][23][24][25], including trace gases on ice [6][7][8][9]13,14].…”

A Monte Carlo simulation study of Nitrogen on LiF(001)

“…One of the interesting systems that widely investigated is the N 2 /NaCl [2] system. Previous Monte Carlo simulations of the adsorbed molecules systems were able to reproduce most of the experimental results [1][2][3], in addition the simulations of the N 2 /NaCl [2] show that this system undergo an order-disorder phase transition with nonuniversal critical exponents and fall in the same universality class as the XY model with cubic anisotropy. The values of the critical exponents depend on the strengths of an anisotropic external potential provided by the substrate (NaCl).…”

“…In the last twenty years, experimental techniques have been improved and made a wealth of information on adsorbate structures at low temperatures, Epitaxial growth and 2D phase transitions, exhibited by molecules adsorbed on solid surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13], available. This was attracting considerable attention for both experimentalists and theoreticians.…”