Meaning of total ground state energy in periodic DFT calculations

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SUMMARY

The total ground state energy in periodic DFT calculations, specifically using VASP, is defined per unit cell rather than as an infinite value. This is due to the implementation of periodic boundary conditions, which simulate an infinite crystal while yielding a finite energy result. Understanding this concept is crucial for interpreting DFT simulation outputs accurately.

PREREQUISITES
  • Familiarity with periodic boundary conditions in computational physics
  • Basic understanding of Density Functional Theory (DFT)
  • Experience with VASP (Vienna Ab-initio Simulation Package)
  • Knowledge of unit cell concepts in crystallography
NEXT STEPS
  • Explore the principles of periodic boundary conditions in DFT simulations
  • Study the implementation of VASP for crystal structure calculations
  • Learn about the interpretation of energy values in DFT outputs
  • Investigate the significance of unit cells in solid-state physics
USEFUL FOR

Researchers and practitioners in computational materials science, particularly those utilizing VASP for periodic DFT calculations and seeking to understand energy interpretations in their simulations.

Derivator
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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
 
Physics news on Phys.org
Yes, it is per unit cell.
 

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