Flex is a simple, portable molecular graphics program that interactively displays 3D ball-and-stick models on workstations running the Xwindows system. Flex can accept input read from a file or passed over a network socket connection. The latter functionality makes flex ideal for monitoring large-scale simulations as they progress. Flex provides a library of subroutines, netg, to support this function. There are other (earlier) versions of Flex available on the net; this one is supported and includes documentation of the communications library.

Flex is accompanied by ffe (flex front end), a program that connects to flex over a socket and allows more precise user control of the displayed molecule.

Flex is freely available by anonymous FTP at ftp.sdsc.edu in the directory /pub/ccms/flex. The README file in that directory contains most if not all of the information you will need. If you have other questions or comments, send e-mail to ccms-help at sdsc dot edu ,or if you have a WWW client that supports forms (e.g. Mosaic 2.0), you may submit comments through the forms interface

Flex is capable of animating sequences of PDB data. Here are some sample animations that were converted to MPEG format by Jeff Mandell.

Molecular dynamics of an insect neuropeptide (426K) by Victoria Roberts, The Scripps Research Institute

This simulation of a small protein molecule was made using Biosym's 'Discover' molecular dynamics program running on a Cray-XMP. Note how the ringed-sidechains approach and withdraw from each other over the course of the simulation.