Error when changing GaAs lattice parameter

[gonzalezm]

I'm trying to calculate the band structure of GaAs and AlAs and I'm following the GaAs example. I obtain the same result showed here: https://ma.issp.u-tokyo.ac.jp/en/app-post/2000#gsc.tab=0. However the bandgap is much smaller than the real value. When trying to discover why I realized that the lattice parameter used in the example is wrong. It should be something like 5.65315 insteal of 10.6867. The problem is that when I try to use the correct lattice parameter I get the error: "STOP 2" when running pw.x < GaAs.scf.in > GaAs.scf.out.

I can't find what it means.

[gonzalezm]

Sorry for the mistake. I just found that the lattice parameter is correct because is supposed to be written in Bohr and not in Angstrom. However the questions about the error when changing the lattice parameter and why the bandgap is not correct remain.

[takeokato719]

In general, it is difficult to realize a band gap in DFT using LDA or GGA (the present calculation is GGA).
GGA usually overestimates the band gap. In the calculation of the MateriApps review, we did not the structure optimization nor spin-orbit coupling. By these factors, the obtained band structure is correct only at a qualitative level.

If you hope to obtain a correct band gap, you should employ another method such as GW, which needs more computational cost.