mirror of https://gitlab.com/QEF/q-e.git
46 lines
2.2 KiB
Plaintext
46 lines
2.2 KiB
Plaintext
This example shows how to obtain a simulated STM image of the AlAs(110)
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surface. The image is obtained by integrating the density of states
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from the bias potential to the fermi energy, as proposed by Tersoff and
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Hamann [PRB 31, 805 (1985)].
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The local density of states contributing to STS is then evaluated as a
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function of energy, with spatial integration in small volumes above
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different surface atoms.
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1) make a self-consistent calculation for the relaxed AlAs (110) surface
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by using a slab supercell.
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(input=AlAs110re.scf.in, ouput=AlAs110re.scf.out)
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2) make a non-self-consistent calculation for the same cell with a larger
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number of k points
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(input=AlAs110re.nonscf.in, output=AlAs110re.nonscf.out)
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3) call the postprocessing executable 'pp.x' with the instruction
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'plot_num= 5' to generate the STM simulated image with bias
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potential specified by 'sample_bias=-0.0735'. Intermediate data
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is collected in file 'AlAsresm-1.0'. A 2-dimensional slice of
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the image is then extracted and written to 'AlAs110-1.0'.
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(input=AlAs110.pp_stm-.in, and output=AlAs110.pp_stm-.out)
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4) same as point 3) but with positive bias 'sample_bias=0.0735'.
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Output files: 'AlAsresm+1.0' and 'AlAs110+1.0'.
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(input=AlAs110.pp_stm+.in, and output=AlAs110.pp_stm+.out)
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5-6) produce a postscript file of the simulated STM images by running the
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executable 'plotrho.x'. This generate the PostScript files
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'AlAs110-1.0eV.ps' and 'AlAs110+1.0eV.ps'.
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(input=AlAs110.plotrho-.in, output=AlAs110.plotrho-.out)
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(input=AlAs110.plotrho+.in, output=AlAs110.plotrho+.out)
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7) computes the local density of states, as function of energy, integrated
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in volumes outside the AlAs(110) surface, for small volumes on top of
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the surface Al and As atoms and at various distances from the surface.
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Output files: 'AlAs110.ldos_boxes' which contains the LDOS(E)
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and 'AlAs110.box#<N>.xsf' with XCrySDen structure files.
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(input=AlAs110.box.projwfc.in, output=AlAs110.box.projwfc.out)
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8) computes the projected density of states (see example08), for comparison.
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(input=AlAs110.projwfc.in, output=AlAs110.projwfc.out)
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9) plot the LDOS and PDOS by using 'gnuplot', if available. This generate
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the PostScript file 'AlAs110.box.projwfc.ps'
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