MacMolPlt is designed to make it easy to visualize output whenever you need it, without needing to specify special output options to GAMESS or having to manually edit files to create an input file. But it is also designed to produce output of good quality such that it can be used in publications. Generally MacMolPlt will read in all the information it needs from a GAMESS log file, but several other file types are supported and you can also paste in coordinates in a variety of cartesian formats including the formats used in GAMESS output files and Gaussian log files.

Once you have data read in you can translate and rotate the molecule using the mouse or manually by entering the molecule center and rotation angles. You can also view orbitals, total electron densities and Molecular Electrostatic Potentials as 2D or 3D surfaces. Depending on the data read in you can animation normal modes, or geometry optimizations, IRC's and DRP's (any file with multiple geometeries).

MacMolPlt includes a standard Macintosh interface for, opening files, saving files, printing, copying, window movement, and display commands. One very nice feature is balloon help support. In most of the dialogs you can turn on balloon help and find out what each control does. Try it out! Rotation in the display window is controlled by the mouse in the same fashion as Chem3D (thanks to public domain code from Apple). The size of the molecule display and various normal mode display options are controlled via the Display menu. Atomic coordinates and bonds can be viewed in separate windows and bonds may be added via a bond radius and/or an automatic bonding feature.

There is also an input builder for GAMESS. It can make it easy to create many GAMESS input files including MO guess and internal coordinates. It doesn't have all advanced options yet, but works quite well for beginners.

Memory usage: MacMolPlt stores all information that it parses from files in its own application partition. Still for modest sized files the default partition size is plenty. Memory for surface grids and for QuickDraw 3D are taken from the system heap so while you do need to have a decent amount of RAM you shouldn't have to change the default partition unless you are opening large files. The only exception to this is when a hi-res PICT is exported with QuickDraw3D active. The large bitmap must be stored in the application partition so you may need extra memory depending on the size of your window.