Parallelisation and porting of UKRMol-in, the electron-molecule scattering inner region R-matrix codes

Paul Roberts
Numerical Algorithms Group Ltd,
Wilkinson House, Jordan Hill Road, Oxford, OX2 8DR, UK,

Date: 1st June, 2012

Abstract:

This dCSE project will concern the parallelization of the SCATCI program within the UKRmol-in suite of codes. For large Hamiltonian systems, most of the compute time within SCATCI was spent on diagonalizing the Hamiltonian matrix and so efforts have focused on parallelizing this part of the SCATCI program. The original project plan was to implement a parallel code, using mixed mode OpenMP/MPI and the PARPACK library. SCATCI has been interfaced with the Scalable Library for Eigenvalue Computations (SLEPc) which is built on top of the well-known PETSc library and the Message Passing Interface (MPI) library. The UKRMol-in suite contains a series of programs, which perform various tasks such as: the calculation of integrals over target and continuum orbitals (and corrections due to the finite size of the R-matrix) and orthogonalisation of the set of orbitals; the construction and diagonalization of the Inner Region Hamiltonian; and in the target run mode the calculation of density matrices and from them target properties. The suite also contains modules to generate Hartree Fock-SCF or pseudonatural orbitals and the basis sets for the description of the continuum. These tasks are fundamental to astrophysics, plasma physics and damage process in biological environments. UKRMol is currently being used to study mechanisms of DNA strand breaking caused by low-energy electron collisions.

This project was approved for 12 months effort in April 2011 and was completed May 2012. The work was supervised by Dr Jimena Gorfinkiel of the Department of Physical Sciences at The Open University. The original candidate was Dr Michael Lysaght who worked on the project from April 2011 until November 2011. Dr Paul Roberts then took over until the conclusion in May 2012.