Gabedit makes using Computational Chemistry Packages (CCP)  simple and straightforward :

• Sketch in molecules using its advanced 3D Structure Builder, or load in molecules from standard files.
• Set up and submit CCP jobs right from the interface, and monitor their progress as they run.
• Examine calculation results graphically via state-of-the-art visualization features: display molecular orbitals and other surfaces, view spectra, animate normal modes, geometry optimizations and reaction paths.
• Simulated Annealing with Molecular Dynamics is implemented in Gabedit (using Amber 99 molecular mechanics parameters).