Unit Cell size

[Nayab Shiraz]

How to select the size of unit cell? I assume enough vacuum around the actual structure is needed. If my results change with change in size of unit cell, do I need to keep increasing the lattice parameters for convergence?

[mlee]

If you need to confirm the vacuum size around the actual structure, you can analyze the HatreeDifferencePotential or ElectrostaticDifferencePotential to see the convergence. 

[Nayab Shiraz]

Thank you so much. Do you mean that these quantities should not change with further increase in size?

[mlee]

You will see the convergence (constant) near the boundary through the HartreeDifferencePotential or ElectrostaticDifferencePotential analysis if it has proper vacuum length.