The formation energy of the silicon (001) surface

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The formation energy of the silicon (001) surface is one of the easier surfaces to calculate, due to the fact that the stoichiometry is that of a single species. The approach outlined below applies to any single species system with a surface.

To calculate the formation energy of a surface you:

  • 1) Simulate a slab of material, ideally as thick as possible and get the total energy from that calculation (DFT, MD etc). This is
  • 2) Simulate the bulk material, and divide by the number of atoms in the basis to get the energy per atom. This
  • 3) Calculate the unit surface area of your slab. This is . Most commonly this is the unit cell dimensions of the two axis parallel to the surface.
  • 3) Solve the following equation.

where is the formation energy (this number is normally given in eV/A2) and is the number of atoms in your slab.