The UCL distorted wave code

The DW code of University College London computes collision strengths and r eactance matrix elements in LS coupling for excitation of atoms and positiv e ions by electron impact in a partial wave expansion. A multiconfiguration al target serves as the scatterer; the partial waves are central field solu tions to a distorted wave (DW) approximation. The DW program is run by linking two source codes: program COLALG and a mod ifying module called DWMODS. In stand-alone mode COLALG creates a file to t he requirements of the electron collision program IMPACT, passing on target data and the angular expansion coefficients of collisional symmetries. Lin ked with DWMODS the program writes a reactance matrix file directly readabl e by JAJOM; the output file OMEGA is compatible with a similar file created by the QUB R-matrix code. Collisional details can be extracted depending u pon the printing level. The UCL macro-processor with the source codes as input creates FORTRAN 77 f iles; apart from replacing size parameters it switches parts of code on and off depending upon directives. (C) 1998 Published by Elsevier Science B.V.