A wave packet method for treating nuclear dynamics on complex potentials

Abstract

A general time-dependent description of the dissociative attachment of a triatomic molecule is presented. The approach presented works within the Feshbach projection operator formalism and gives an algorithm for solving the nuclear motion problem which reduces the computational effort required. The method uses a complex potential energy surface to characterize the formation and decay of resonances as modified by the coupling to the nuclear motion which are treated using multidimensional complex wave packets. A basis-independent wave packet method is developed and used to treat the propagation of a wave packet on a complex three-dimensional potential appropriate for resonance states of the water anion. A complete derivation of the system of linear equations used in the time iteration is presented. The method can be applied to resonant vibrational excitation, for which the electron impact vibrational excitation of water is considered.

Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

“…The efficient decay of valence hole with the emission of a low-energy electron (<11 eV) in C, as shown in this paper, can be an important pathway in radiation damage of living tissues. Low energy electrons (<20 eV) have been shown to be very effective in causing DNA strand breaks through dissociative electron attachment 17 18 19 .…”

Relative Role of Physical Mechanisms on Complex Biodamage Induced by Carbon Irradiation

“…The physical processes that can lead to damage can be recorded by means of the SEED code. , The following damaging mechanisms were considered: (i) ionizations, (ii) electronic excitations leading to bond dissociation, and (iii) dissociative electron attachment events; the latter was simulated using the experimental cross section available for water molecules. ,, We assumed that only 40% of electronic excitation events lead to molecular dissociation and thus produce damage. Figure shows the average cluster size M 1 of damaging events scored in nanometric cylinders of liquid water with a 2.3 nm diameter and a 6.8 nm height (see the inset in Figure ), which is the size of 20 base pairs (bp) of DNA, for several carbon-ion energies T and impact parameters 0 ≤ r ≤ 100 nm.…”

On the relative role of the physical mechanisms on complex biodamage induced by carbon irradiation

“…We considered as damaging mechanisms: i) ionizations, ii) electronic excitations leading to bond dissociation, iii) and DEA events, the latter being simulated using the experimental cross section available for water molecules [33,49]. We have assumed that only 40% of electronic excitation events lead to molecular dissociation [43] and thus produce damage.…”