Superposition calculation
The superposition calculation (superpos
in the code) is the last section
of “classic” TensErLEED and is automatically executed by viperleed.calc
after the
structure search.
It takes the delta files and the result of the structure search — which at that point is only a set of optimized parameters — and performs the name-giving superposition: it adds the sum of delta amplitudes corresponding to the optimal parameters to the reference amplitudes, producing a final set of total beam amplitudes and intensities in the same format as yielded by the Reference calculation.
ViPErLEED processes the intensities to the FITBEAMS file. It then calculates the \(R\) factor between these beams and those in the EXPBEAMS file, producing the Rfactor_plots_superpos.pdf and Rfactor_analysis_superpos.pdf files (see the corresponding sections for details and examples).
Note
It is recommended to run another reference calculation for the final structure, as the FITBEAMS contain errors due to the tensor-LEED approximation.