Both the eFF computation and eFFview visualization software are released under a BSD license, i.e. they are free to use, distribute, and modify in both source and binary form provided that a copyright and permission notice remain attached. The full license is given in the Programmer's Guide.
eFF is a command-line program that computes the energy and forces associated with a configuration of nuclei and electrons. The overall energy may be minimized to obtain ground states, or semiclassical dynamics may be propagated to obtain excited electron motions. Periodic boundaries may be applied, and thermodynamic functions such as temperature and pressure may be computed. Further details are given in the User's Guide.
The computational cost of eFF scales linearly with the total number of particles if pairwise cutoffs are used. This makes it practical to perform dynamics on nonperiodic and periodic systems containing many thousands of electrons. Memory usage is linear with the total number of nuclei and electrons. All memory is dynamically allocated, so that the system size is limited only by the memory installed in the computer.
eFFview is an interactive OpenGL program which generates high quality still frames and movies of nuclear and electron dynamics from eFF input and output files. Nuclei are displayed as balls and sticks, and electrons are displayed as spheres whose sizes vary with time. An example of the different displays eFFview can generate is shown below.
A variety of graphical options can be specified interactively, or via a configuration file. Many of the figures on this website were created using eFFview.
The eFF distribution contains: