Constructing the Standard Version

DL_POLY_2 was designed as a package of useful subroutines rather than a single program, which means that users are to be able to construct a working simulation program of their own design from the subroutines available, which is capable of performing a specific simulation. However we recognise that many, perhaps most, users will be content with creating a standard version that covers all of the possible applications and for this reason we have provided the necessary tools to assemble such a version. The method of creating the standard version is described in detail in this chapter, however a brief step-by-step description follows.

1. DL_POLY_2 is supplied as a UNIX compressed tar file. This must uncompressed and un-tared to create the DL_POLY_2 directory (section 1.5).
2. In the build subdirectory you will find the required DL_POLY_2 makefile (see section 3.2.1 and Appendix A.1, where the main Makefile is listed). This must be copied into the subdirectory containing the relevant source code. In most cases this will be the source subdirectory.
3. The makefile is executed with the appropriate keywords (section 3.2.1) which select for specific computers and if a parallel machine is used, the appropriate communication software.
4. The makefile produces the executable version of the code, which as a default will be named DLPOLY.X and located in the execute subdirectory.
5. DL_POLY also has a Java GUI. The files for this are stored in the subdirectory java. Compilation of this is simple and requires running the javac compiler and the jar utility. Details for these procedures are provided in the GUI manual [9].
6. To run the executable for the first time you require the files CONTROL, FIELD and CONFIG (and possibly TABLE if you have tabulated potentials). These must be present in the directory from which the program is executed. (See section 4.1 for the description of the input files.)
7. Executing the program will produce the files OUTPUT, REVCON and REVIVE (and optionally STATIS, HISTORY, RDFDAT and ZDNDAT) in the executing directory. (See section 4.2 for the description of the output files.)

This simple procedure is enough to create a standard version to run the supplied test cases. (For versions preceeding 2.11, it will not run the larger benchmark cases however.) Creating a larger executable, or one which is tailored to an application different from the test cases is more complicated. The main difficulty centres on assigning appropriate array dimensions to meet the application's needs. In versions of DL_POLY_2 after 2.11 these dimensions are calculated by the subroutine PARSET.F and its support routines CFGSCAN.F, CONSCAN.F and FLDSCAN.F. These support routines scan the CONFIG, CONTROL and FIELD files at the start of a run and estimate the required array sizes. (A description of the individual arrays found in DL_POLY_2 is provided in Appendix C of the DL_POLY_2 Reference Manual.)

In versions preceeding 2.11, the size of the DL_POLY_2 executable is determined by the the DL_PARAMS.INC (include) file (see section 8.1.1), which specifies all the FORTRAN parameters of the code and is included in each subroutine at compile time. This file is found in the source directory and is internally documented (it is also documented in chapter 8). Reconstructing the DL_PARAMS.INC for a new simulation is the most difficult aspect of preparing a DL_POLY_2 executable. If the parameters are not appropriate, DL_POLY_2 will complain if any parameter is too small and abort in execution. Each such error will entail a recompilation of the code, and DL_POLY_2 generally detects only one error at a time! Fortunately, the process of creating a new DL_PARAMS.INC file is greatly assisted by the utility program PARSET (see section 7.1.1). Provided the CONTROL, CONFIG and FIELD files are available, PARSET will create a suitable parameters file for you. (See section 3.2.2).