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I was doing some calculations involving Selenium (my advisor gave me this "task" as training. I'm an undergraduate student.), which exposes the Weyl nodes in its band structure, and I tried to replicate those points. However, I was unable to observe the nodes in the band structure, although the general characteristic of the graph is similar and so is the gap (SOC) and the lattice parameters are similar to those reported in other papers. I tried Q.E (Quantum Espresso) but I got the same result.

What could be compromising the emergence of these nodes? I tried denser KPOINTS,different KPATH, relaxation, etc.

INCAR (SOC_SCF) (15x15x8) and INCAR (SOC_BAND) + KPATH (Gamma > M > K > GAMMA > A > L > H > A)

ISTART = 0 (Read existing wavefunction, if there) ISPIN = 1 (Non-Spin polarised DFT) LREAL = .FALSE. (Projection operators: automatic) ENCUT = 520 (Cut-off energy for plane wave basis set, in eV) PREC = Normal LWAVE = .False. (Write WAVECAR or not) LCHARG = .TRUE. (Write CHGCAR or not) ADDGRID= .TRUE. (Increase grid, helps GGA convergence) ISMEAR = 0 (gaussian smearing method) SIGMA = 0.03 (please check the width of the smearing) LORBIT = 11 (PAW radii for projected DOS) NEDOS = 6001 (DOSCAR points) NELM = 60 (Max electronic SCF steps) EDIFF = 1E-06 (SCF energy convergence, in eV) LSORBIT = .TRUE. (Activate SOC) LNONCOLLINEAR = .TRUE.

the crossing point is at point H (bandgap region). Path: Gamma > M > K > GAMMA > A > L > H > A

The crossing point is at point H (bandgap region). Path: Gamma > M > K > GAMMA > A > L > H > A

PS: I think the problem is in the number of points per line in KPATH.

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    $\begingroup$ +1 Could you please show the bandstructure you have calculated, preferred that place the one you are comparing with right next to each other. The number of points per line would affect how smooth the line is but not the location of the nodes (if they exist), you are probably not using the right K-path, but I can't tell without looking at the figure. $\endgroup$ Commented Apr 3, 2024 at 7:22
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    $\begingroup$ Your pastebin links are not accessible from certain geographic locations. For example, I cannot access them. Since they are INCAR files, they are not that large I believe. Could you simply copy-paste the content of those files as code blocks? See this $\endgroup$ Commented Apr 3, 2024 at 10:54
  • $\begingroup$ I've added the extra info. $\endgroup$ Commented Apr 3, 2024 at 18:27
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    $\begingroup$ @GabrielElyas. Have you tried without SOC? $\endgroup$ Commented Apr 4, 2024 at 1:18

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The problem was really the number of points per line in KPATH. enter image description here

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