Use the Surface Properties node to define the density of sites, the site occupancy number, and the surface diffusion.

The Compensate for boundary stretching check box is selected by default. Click to clear the check box if required.

Enter a value or expression for the Density of sites Γs (SI unit: mol/m2). The default is 2 x 10-5 mol/m2.

Enter a Site occupancy number σi (dimensionless), indicating how many surface sites a surface species block upon adsorption.

Select a Surface material from the list. The default is None.

For each surface concentration species, the default Diffusion coefficient Di (SI unit: m2/s) is User defined. Select Isotropic, Diagonal, Symmetric, or Anisotropic depending on the characteristics of the surface, and then enter values or expressions in the field or matrix.

For each bulk species enter the Molar mass Mi (SI unit: kg/mol) and the Density ρi (SI unit: kg/m3). The default molar mass is 0.144 kg/mol and the default density is 5320 kg/m3).