Quantum-mechanical comparative study of ground states in Fe3Al
Tomáš Komárek1,2*
, Monika Všianská1,3
, Martin Friák3,1
, Mojmír Šob1,3,2
1
Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 753/5,
625 00 Brno, Czech Republic
2
Faculty of Science, Department of Chemistry, Masaryk University, Kotlářská 267/2, 611 37 Brno,
Czech Republic
3
Institute of Physics of Materials, ASCR, v.v.i., Žižkova 22, 616 62 Brno, Czech Republic
*255559@mail.muni.cz
Keywords: ab initio, DFT, Fe3Al, ground state
There is a long-lasting problem with quantum-mechanical calculations and their incorrect prediction
of the ground-state structure of Fe3Al. Many exchange-correlation functionals lead to the preference
of the L12 structure instead of experimentally found D03 phase. Using the VASP code we calculated
energy-volume curves for five exchange-correlation functionals combined with six different
projector-augmented-wave potentials. The exchange-correlation functionals employed are
Perdew-Wang 91 (PW91), Perdew-Burke-Ernzerhof (PBE), revised Perdew-Burke-Ernzerhof
(rPBE), Armiento-Mattson (AM05), and Perdew-Burke-Ernzerhof revised for solids (PBEsol).
The projector-augmented-wave potentials for Fe and Al are GGA (Fe), GGA with p semi-core states
treated as valence states (Fepv), PBE potentials (PBE), PBE with p semi-core states treated
as valence states (PBEpv), potentials used for GW calculations (GW) and GW with s and p semicore
states treated as valence states (GWsv). We used the energy preference of the D03 structure
as the most important criterion: the energy difference E(D03) – E(L12) was calculated and
combinations that prefer L12 structure were not considered. Lattice parameter was the second
criterion: combinations exhibiting a difference from the experimental value larger than 2%
difference were rejected. Finally, we analyzed also the differences between the calculated and
experimental bulk modulus. Considering the above mentioned criteria, we select
the Perdew-Wang 91 exchange-correlation functional using Vosko-Wilk-Nusair interpolation for
description of the ground state of Fe3Al. Here the energy difference E(D03) – E(L12) varies from
-4.45 to -7.10 meV/atom, the difference between the calculated and experimental lattice constant
lies between -0.85 and -1.01% and the calculated bulk modulus differs from the experimental one
by values within the range from 22.7 to 23.6%.
Figure 1 Energy difference of E(D03)–E(L12) for different combinations of exchange-correlation functionals and
projector-augmented-wave potentials in Fe3Al calculation.