Total energy

[luiz.silveira]

Greetings,

According to the theory presented so far the DFT calculated energy should be composed by these contributions: electrons kinetic energy, electron-nuclei interaction energy, electron-electron interaction energy, and exchange-correlation energy. In Quantum Espresso output file the total energy is decomposed in the following terms:

one-electron contribution
hartree contribution
xc contribution
ewald contribution
one-center paw contribution
smearing contribution (-TS)

The first three terms are electron kinetic energy (I guess), electron-electron interaction energy, and exchange-correlation energy. What are the last three terms? Does any of them represent electron-nuclei interaction energy?

Regards,
Luiz

[admin-compmatphys]

The ewald contribution is the nucleus-nucleus interaction (see https://en.wikipedia.org/wiki/Ewald_summation for a general discussion). The one-center paw contribution is a mathematical consequence of using these particular pseudopotentials and plane waves. The smearing contribution is an ad hoc correction to extract the energy that would be found without smearing from a calculation with smearing (we did not discuss smearing in this course — it is a mathematical trick to speed up convergence of the scf-cycle by replacing the exact one-particle energies by slightly broadened ones. To be imagined as an artificial temperature.)

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