Author Topic: TotalEnergy is not supported for MGGA?  (Read 3936 times)

0 Members and 1 Guest are viewing this topic.

Offline 395235863

  • Heavy QuantumATK user
  • ***
  • Posts: 81
  • Country: cn
  • Reputation: 0
    • View Profile
TotalEnergy is not supported for MGGA?
« on: October 28, 2016, 05:11 »
How to calculate the energy by DFT-mGGA?
Thank you!

Offline Petr Khomyakov

  • QuantumATK Staff
  • Supreme QuantumATK Wizard
  • *****
  • Posts: 1290
  • Country: dk
  • Reputation: 25
    • View Profile
Re: TotalEnergy is not supported for MGGA?
« Reply #1 on: October 28, 2016, 09:19 »
The MGGA-TB09LDA is a potential-only  functional, meaning that it is not designed to calculate the total energy and forces. It can be used to calculate the electronic structure for a given geometry of the system. The geometry can be first optimized with standard LDA or GGA functional by doing total energy calculations, and the MGGA functional can then be adopted to get a more accurate band structure of semiconductors, for example.

Offline 395235863

  • Heavy QuantumATK user
  • ***
  • Posts: 81
  • Country: cn
  • Reputation: 0
    • View Profile
Re: TotalEnergy is not supported for MGGA?
« Reply #2 on: October 28, 2016, 09:25 »
But in paper http://dx.doi.org/10.1103/PhysRevB.86.075149 ,Table I gives the energy in mGGA.

Can ATK do this ? Thank you!

Offline Petr Khomyakov

  • QuantumATK Staff
  • Supreme QuantumATK Wizard
  • *****
  • Posts: 1290
  • Country: dk
  • Reputation: 25
    • View Profile
Re: TotalEnergy is not supported for MGGA?
« Reply #3 on: October 28, 2016, 11:11 »
It is not about ATK. MBJ-MGGA is not designed to be used for self-consistent total energy calculations in any DFT code; you may see a note about it at http://cms.mpi.univie.ac.at/wiki/index.php/METAGGA. You may still find some metagga-derived energy in ATK log file, but the question is whether this energy makes any real physical sense or relevance.