Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
VMD (Visual Molecular Dynamics) is designed for the visualization and analysis of biological systems such as proteins, nucleic acids, lipid bilayer assemblies, etc. It may be used to view more general molecules, as VMD can read standard Protein Data Bank (PDB) files and display the contained structure. VMD provides a wide variety of methods for rendering and coloring a molecule: simple points and lines, CPK spheres and cylinders, licorice bonds, backbone tubes and ribbons, cartoon drawings, and others. VMD can be used to animate and analyze the trajectory of a molecular dynamics (MD) simulation. In particular, VMD can act as a graphical front end for an external MD program by displaying and animating a molecule undergoing simulation on a remote computer. VMD uses OpenGL and OpenGL Programmable Shading Language for high performance rendering of large structures.
FlipDCD is a small utility for reversing the endianism of binary DCD trajectory files from Charmm and NAMD. This can be useful when running simulations on one architecture and visualizing or analyzing the results on another. FixDCD is a tiny utility to modify the header of an X-PLOR DCD file to make it readable by programs expecting Charmm DCD files, at the expense of a Timestep size value in the header.
MatDCD is a Matlab package for reading/writing DCD-formatted molecular dynamics trajectory files. It supports Charmm and xplor-format DCD files, it can read both big- and little-endian storage formats, and it can specify which atom indices to load without having to load the entire file.
Mol_Volume calculates the volume of a macromolecule by a method somewhat akin to the Monte Carlo method, namely, by measuring how many vertices of a dense regular grid happen to be within the probe radius of the molecule's atoms. The volume is then calculated as V = V_grid * N_near / N_total = N_near * V_per_node.
PDBCat can be used to manipulate and process PDB files using commonly available text-processing tools such as Perl, awk, etc. The Brookhaven Protein Data Bank stores atomic coordinate information for protein structures in a column-based format which is designed to be read easily read by FORTRAN programs. PDBCat converts the ATOM and HETATM records of PDB files from this column-based format to a field-based one that is more easily processed by standard Unix tools.
SODIUM places the required number of sodium ions around a (simulated) system of electric charges, e.g., the atoms of a biological macromolecule (protein, DNA, protein/DNA complex). The ions are placed in the nodes of a cubic grid in which the electrostatic energy achieves the smallest values. The energy is re-computed after placement of each ion. A simple Coulombic formula is used for the energy. The coordinates of the placed ions are printed out in the PDB format for further usage. Trivial modifications to the program should allow the placement of any combination of multivalent ions of different charges.