I'm working with the Siesta DFT software, and managed to reproduce the band structure of bulk Si without any issues. However, when trying the same with a Si nanowire, the band structure looks nowhere near those published in literature, and there doesn't seem to be any bandgap either. Has anyone had previous experience with a similar situation?
SystemName Si
SystemLabel Si
NumberOfSpecies 1
NumberOfAtoms 85
%block ChemicalSpeciesLabel
1 14 Si
%endblock ChemicalSpeciesLabel
LatticeConstant 5.41 Ang
%block LatticeVectors
16.00 0.00 0.00
0.00 1.00 0.00
0.00 0.00 16.00
%endblock LatticeVectors
AtomCoorFormatOut Ang
AtomicCoordinatesFormat Ang
%block AtomicCoordinatesAndAtomicSpecies
35.1650000000 0.0000000000 35.1650000000 1
36.5175000000 1.3525000000 36.5175000000 1
...
51.3950000000 2.7050000000 48.6900000000 1
50.0425000000 1.3525000000 50.0425000000 1
%endblock AtomicCoordinatesAndAtomicSpecies
%block kgrid_Monkhorst_Pack
1 0 0 0.5
0 16 0 0.5
0 0 1 0.5
%endblock kgrid_Monkhorst_Pack
PAO.BasisSize DZP
XC.functional LDA
XC.authors CA
SpinPolarized .false.
MeshCutoff 300 Ry
kgrid_cutoff 100.0 Ang
MD.TypeOfRun CG
MD.VariableCell true
MD.NumCGsteps 50
MD.MaxCGDispl 0.1 Bohr
MD.MaxForceTol 0.01 eV/Ang
MD.MaxStressTol 0.0001 eV/Ang**3
%block GeometryConstraints
%endblock GeometryConstraints
MD.UseSaveXV true
MaxSCFIterations 100
DM.MixingWeight 0.01
DM.NumberPulay 3
DM.Tolerance 1.d-3
ElectronicTemperature 25 meV
SolutionMethod diagon
BandLinesScale pi/a
%block BandLines
1 0.0000000000 0.0000000000 0.0000000000 \Gamma
50 0.0000000000 1.0000000000 0.0000000000 Y
%endblock BandLines
%block WaveFuncKPoints
0.000 0.000 0.000 from 1 to 20
%endblock WaveFuncKPoints