Example: LDOS (STM) for a BN slab¶

# The BN slab has a band gap
# The bottom of the conduction band  (BOCB, 0.05 hartree above the fermi level)  consists of p_z orbitals on B
# The top of the valence band (TOVB, 0.2 hartree under the fermi level)  consists of p_z oribtals on N

# It is recommended to inspect BNSlab.results with amsbands
# and BNSlab.ldos.tovb.results with amsview (and the same for bocb)

system=BNSlab

export AMS_JOBNAME=$system

rm -rf $AMS_JOBNAME.results

$AMSBIN/ams<<EOF

Task SinglePoint

System
   Atoms
		B      -0.615000000    -0.355070416     0.000000000
		N       0.615000000     0.355070416     0.000000000
    End
	Lattice
	     2.460000000     0.000000000     0.000000000
	     1.230000000     2.130422493     0.000000000
End

End

Engine Band
	BandStructure Enabled=yes
	Dos CalcPDOS=yes
	kspace quality=good
EndEngine

EOF

fermi_energy=`$AMSBIN/amsreport $AMS_JOBNAME.results/band.rkf -r "BandStructure%FermiEnergy"`
bcb=`$AMSBIN/amsreport $AMS_JOBNAME.results/band.rkf -r "BandStructure%BottomConductionBand"`
tvb=`$AMSBIN/amsreport $AMS_JOBNAME.results/band.rkf -r "BandStructure%TopValenceBand"`

echo "Fermi energy (Hartree): $fermi_energy"
echo "tvb (Hartree): $tvb"
echo "bcb (Hartree): $bcb"

rel_tvb=`$AMSBIN/amspython -c "print($fermi_energy-$tvb)"`
rel_bcb=`$AMSBIN/amspython -c "print($bcb-$fermi_energy)"`

echo "rel_bcb (Hartree): $rel_bcb"
echo "rel_tvb (Hartree): $rel_tvb"

# we want to sample just a bit above/below the bcb and tvb: both need a margin
# the applied margins here are quite arbitrary, but ensure that the example works exactly as before

rel_tvb_with_margin=`$AMSBIN/amspython -c "print($rel_tvb+0.0585153984080739)"`
rel_bcb_with_margin=`$AMSBIN/amspython -c "print($rel_bcb+0.0205273425101303)"`

echo "rel_bcb_with_margin (Hartree): $rel_bcb_with_margin"
echo "rel_tvb_with_margin (Hartree): $rel_tvb_with_margin"


export AMS_JOBNAME=$system.ldos.bocb

rm -rf $AMS_JOBNAME.results


$AMSBIN/ams  --delete-old-results << EOF
Task SinglePoint

LoadSystem 
    File $system.results/ams.rkf
End

Engine BAND
Restart
   File $system.results/band.rkf
   DensityPlot
End

Grid
   Type Coarse
End

DensityPlot
   LDOS
End

LDOS
   DeltaNeg 0.0 # fermi energy, halfway the gap
   DeltaPos $rel_bcb_with_margin   # bit above the bcb
End
EndEngine
EOF



export AMS_JOBNAME=$system.ldos.tovb

rm -rf $AMS_JOBNAME.results


$AMSBIN/ams  --delete-old-results << EOF
Task SinglePoint

LoadSystem 
    File $system.results/ams.rkf
End

Engine BAND
Restart
   File $system.results/band.rkf
   DensityPlot
End

Grid
   Type Coarse
End

DensityPlot
   LDOS
End

LDOS
   DeltaNeg $rel_tvb_with_margin  # bit below the tvb
   DeltaPos 0.0 # fermi energy, halfway the gap
End
EndEngine
EOF


echo "Begin TOC of tape41 (tovb)"

$AMSBIN/dmpkf -n 1 $system.ldos.tovb.results/TAPE41 --toc | grep LDOS

echo "End TOC of tape41"


echo "Begin TOC of tape41 (bocb)"

$AMSBIN/dmpkf -n 1 $system.ldos.bocb.results/TAPE41 --toc | grep LDOS

echo "End TOC of tape41"