The ability to model and understand electron-molecule scattering processes is of fundamental relevance in a variety of research and technology areas: astrophysics, plasma physics, the understanding of the damage process initiated by ionising radiation in biological environments (the cell), etc.. The methodology to treat these processes at low projectile kinetic energies (below the ionisation threshold) is fairly well developed. In particular, the UK has been at the forefront of the field, with use of the R-matrix method to treat the problem in an ab initio manner. Specifically, the UK R-matrix polyatomic suite [1], UKRMol, is one of the most accurate codes in the world to describe the electronic part of the problem. These codes are also used to study positron scattering. Radiation uses in medicine (for treatment and diagnosis) have been developed for many decades mostly as empirical macroscopic techniques. However, recent important biomedical advances involving radiation are demanding an increasingly detailed level of description of the nanoscale, molecular interaction processes involved. Experiments confirmed almost a decade ago that secondary electrons with energies up to 20 eV can damage DNA [2]. Detailed experimental studies with DNA strands and DNA/RNA constituents have confirmed that electron collisional mechanisms (such as dissociative electron attachment) are highly efficient in producing structural changes leading to biological and physiological alterations. This intense experimental activity [3] has not been matched by theoretical studies, with such work tackling only the completely elastic process. Exceptions are the studies of uracil [4] and the sugar molecule tetrahydrofuran using the R-matrix codes [5]. Application of UKRMol to other new fields like near threshold ionisation [6] have also recently been pioneered.
The atomic versions of the R-matrix codes (PRMAT) have been ported and optimized on HECToR (by Dr M Plummer and Dr A G Sunderland) in a previous dCSE project and there is further dCSE funded work to interface the PFARM part of PRMAT with the UKRMOL-in suite of codes and to parallelize the construction of the atomic Hamiltonian (Dr M Plummer).
The UKRMol-in suite contains a series of programs, see Figure , which perform the following tasks: