Contribution from inelastic scattering to the validity of trajectory methods

Highlights: •Validity of trajectory methods is studied using random point scatterer clusters. •Validity found for elastic scattering if wavelength/interscatterer distance <1. •Frequent inelastic scattering extends range of validity to larger wavelengths. •Indicates validity possible down to a few eV for electrons in liquid water. -- Abstract: Previous calculations of elastic particle scattering in clusters of randomly distributed point scatterers have shown that Monte Carlo trajectory simulation may be valid as an approximation of quantum multiple elastic scattering, provided that the particle wavelength is about equal to or smaller than the average distance dnn between nearest neighbour scatterers. For the biologically important case of electrons in liquid water, this suggests that trajectory simulation of multiple elastic scattering may be valid (less than 5% error) for electron energies down to about 15 eV. Short range order increases the error somewhat, and produces, as well known, manifest diffraction effects under single scattering conditions. Present similar calculations show that trajectory simulation may be a reasonably good approximation also for particles with wavelengths substantially larger than dnn, if plural or multiple inelastic scattering is introduced. This suggests that for electrons in liquid water trajectory simulation might, depending on the nature and frequency of inelastic scattering, be valid as an approximation at electron energies as low as a few eV