Hello,

I am trying to calculate the formation energy of a charged point defect in UO2 using the supercell method. Therefore, a corrective term must be taken into account to consider the interaction of the charged defect with its images. For this, I use the Leslie and Gillan correction term (M Leslie and N J Gillan 1985 J. Phys. C: Solid State Phys. 18 973), namely:

Ecorr =(q^2 * a)/(2 * epsilon * L).

However, I have several questions regarding this term:

- Is the term epsilon indeed the absolute permittivity of the material and is therefore equal to epsilon = epsilon_r * epsilon_zero​?

- When I apply this formula in the case of a uranium vacancy charged -4, I find a correction that seems high ( Ecorr= ( 4 * 1.602*10^-19 )^2 * 2.837 / ( 2 * 22 * 8.854*10 ^-12 * 11 * 10^-10)=~17 eV ). Is this correct or am I forgetting something?

Thank you for the time you would grant me.