DL_POLY_2 is, for the most part, self contained and does not require access to many additional program libraries. The required program libraries for parallel execution are standard MPI. The other exception is the need for 3D Fast Fourier Transform (FFT) routines in the Smoothed Particle Mesh Ewald (SPME) method introduced in Version 2.12. For applications on Cray T3E/D and IBM SP/2 computers the required routines are readily available in the scientific subroutine libraries (routines ccfft3d and dcft3 respectively). For other machines an internal 3D FFT routine (dlpfft3) is available as a default, though users may prefer the public domain FFT routine fftwnd_fft for optimal performance.