Regarding electronic structure is there any relation to reduction of lattice constants and GGA approach?
Hi Dr M.A. Hadi,
This fact is directly related to the improper account of electron-electron correlations (hartree and Hartree Fock electron-electron correlations) in the GGA approximation.
GGA under-estimates these correlation and therefore over-estimates lattice parameters and under-estimates energy bandgaps.
LDA approximation gives the reverse results (underestimates lattices parameters and overestimates energy bandgaps) but LDA is often closer to experimental values than GGA.
In fact there are several other approximations within DFT-Full Potential as well as DFT-Pseudo-Potential approaches, see following references for better insight:
- DFT approximations: Which one to use ? by P. Blaha and F. Tran
https://icamm2019.sciencesconf.org/data/pages/2019_ICAMM_dft_blaha.pdfgives
- Accurate Band Gaps for Semiconductors from Density Functional Theory Hai Xiao, Jamil Tahir-Kheli, and William A. Goddard, The journal of Physical Chemistry Letters,https://core.ac.uk/download/pdf/4888374.pdf
Good luck and keep safe,
Best regards,
Professor A. Kadri
Thank you dear professor Abderrahmane Kadri for your nice discussion and providing useful links. Stay safe by the grace of almighty Allah.
Best Regards,
M.A. Hadi
Thank you Zahra Mollaei for nice discussion. Stay safe with your family, relatives and friends.
Best wishes,
M.A. Hadi
Dear Dr. M A Hadi
In GGA, exchange correlation density depends on both electronic density and gradients of electron density which improves the lattice parameters,,
There could be further improvement in lattice constants by using the hybrid functional.
GGA is better than LDA and another approximations because it treat electron density gradiently and gives us good results.
- Badges
- Science topic
- Similar topics
- Filing