The CONFIG file and the FIELD file can be quite large and unwieldy particularly if a polymer or biological molecule is involved in the simulation. This section outlines the paths to follow when trying to construct files for such systems. The description of the DL_POLY_2 force field in chapter 2 is essential reading. The various utility routines mentioned in this section are described in greater detail in chapter 7. Many of these have been incorporated into the DL_POLY_2 Graphical User Interface [9] and may be convienently used from there.