ATTENUATION_EPS

ATTENUATION_EPS (corresponds to FORTRAN parameter TST in beamgen, refcalc and search routines) controls which beams will be considered or not when plane-wave propagation occurs between neighboring layers. Specifically, the program will (i) propagate all beams between two neighboring layers, and (ii) keep all those beams that got attenuated by a factor of less than ATTENUATION_EPS to interact with the next layer.

Default: ATTENUATION_EPS = 0.001

Syntax

ATTENUATION_EPS = 0.005

Acceptable values: 1e-6 < ATTENUATION_EPS < 1

Note

  • This parameter can usually be left to its default value. Tweaking (typically increasing) it can help convergence only in those cases in which the minimum interlayer distance goes below 1.0 Å.

  • Smaller values will increase the calculation time as more beams will be considered.

  • Small values of ATTENUATION_EPS can lead to numerical instabilities and the calculation of the beam intensities.

Changelog

Changed in version TensErLEED: 1.61 The lower limit was changed from 1e-4 to 1e-6 (read by FORTRAN as a F7.4).