14 research outputs found
Low and intermediate energy electron collisions with the C molecular anion
Calculations are presented which use the molecular R-matrix with
pseudo-states (MRMPS) method to treat electron impact electron detachment and
electronic excitation of the carbon dimer anion. Resonances are found above the
ionisation threshold of C with , and
symmetry. These are shape resonances trapped by the effect of an attractive
polarisation potential competing with a repulsive Coulomb interaction. The
resonances are found to give structure in the detachment cross section
similar to that observed experimentally. Both excitation and detachment cross
sections are found to be dominated by large impact parameter collisions whose
contribution is modelled using the Born approximation.Comment: 18 pages, 5 figures constructed from 8 file
Convergent calculations of positron scattering from molecular hydrogen
An overview is given of the recently developed adiabatic-nuclei convergent closecoupling method for positron-molecule scattering. Fixed-nuclei single-centre calculations of positron-H2 scattering are presented. Particular emphasis is given to demonstrating convergence with increasing size of the basis and the projectile partial-wave expansion. Results are converged to within ±5%
QDB: A new database of plasma chemistries and reactions
One of the most challenging and recurring problems when modeling plasmas is the lack of data on the key atomic and molecular reactions that drive plasma processes. Even when there are data for some reactions, complete and validated datasets of chemistries are rarely available. This hinders research on plasma processes and curbs development of industrial applications. The QDB project aims to address this problem by providing a platform for provision, exchange, and validation of chemistry datasets. A new data model developed for QDB is presented. QDB collates published data on both electron scattering and heavy-particle reactions. These data are formed into reaction sets, which are then validated against experimental data where possible. This process produces both complete chemistry sets and identifies key reactions that are currently unreported in the literature. Gaps in the datasets can be filled using established theoretical methods. Initial validated chemistry sets for SF 6 /CF 4 /O 2 and SF 6 /CF 4 /N 2 /H 2 are presented as examples
Electron-molecule collisions at low and intermediate energies using the R-matrix method
We present the latest developments of the R-matrix method as applied
to electron-molecule collisions. A variety of calculations for H2O
are presented including the study of rotational excitation and
preliminary data for dissociative electron attachment. Results for the
application of the recently developed molecular R-matrix with
pseudostates (MRMPS) method to neutral and cationic targets are also
included. This method is currently being applied to the study of
collisions with anionic targets
UKRmol: a low-energy electron- and positron-molecule scattering suite
We describe the UK computational implementation of the R-matrix method for the treatment of electron and positron scattering from molecules. Recent developments in the UKRmol suite are detailed together with the collision processes it is enabling us to treat