Meaning of total ground state energy in periodic DFT calculations

[Derivator]

Dear all,

periodic DFT codes (e.g. VASP) effectively simulate an infinite crystal due to the periodic boundary conditions. However, the energy value that one obtaines at the end of a simulation if finite. Frankly, I'm quite confused right now.

Is the energy to be understood 'per unit cell'? Why is the energy value not infinite?

Cheers,
derivator

 

[DrDu]

Yes, it is per unit cell.