The utility GENLAT can be used to construct the CONFIG file for relatively simple lattice structures. Input is interactive. The FIELD file for such systems are normally small and can be constructed by hand. The utility GENLAT.TO constructs the CONFIG file for truncated-octahedral boundary conditions. Otherwise the input of force field data for crystalline systems is particularly simple, if no angular forces are required (notable exceptions to this are zeolites and silicate glasses - see below). Such systems require only the specification of the atomic types and the necessary pair forces. The reader is referred to the description of the DL_POLY_2 FIELD file for further details (section 4.1.3).
DL_POLY_2 allows the simulation of zeolites and silicate (or other) glasses. Both these materials require the use of angular forces to describe the local structure correctly. In both cases the angular terms are included as three body terms, the forms of which are described in chapter 2. These terms are entered into the FIELD file with the pair potentials. Note that you cannot use truncated octahedral or rhombic dodecahedral boundary conditions in conjunction with three body forces, due to the use of the link-cell algorithm for evaluating the forces.
An alternative way of handling zeolites is to treat the zeolite framework as a kind of macromolecule (see below). Specifying all this is tedious and is best done computationally: what is required is to determine the nearest image neighbours of all atoms and assign appropriate bond and valence angle potentials. (This may require the definition of new bond forces in subroutine BNDFRC, but this is easy.) What must be avoided at all costs is specifying the angle potentials without specifying bond potentials. In this case DL_POLY_2 will automatically cancel the non-bonded forces between atoms linked via valence angles and the system will collapse. The advantage of this method is that the calculation is likely to be faster using three-body forces. This method is not recommended for amorphous systems.