Ab initio packages for starters
|PCGamess: Ab initio code for your Windows PC|
|MacMolplt: Nice visualization of Gamess output|
|Arguslab: Visualize or draw molecules, optimize with molecular dynamics, useful to generate starting geometries|
|Mopac: Molecular dynamics and semiempirical methods|
Suggested sequence for simple structure calculations:
(1) Draw your molecule in CHEMSKETCH and push the ‘optimize 3D’ button, save it in .mol format
(2) I used OPENBABEL to convert the .mol coordinates to Gamess input format.
(4) Use the PM3 structure result to start a DFT (B3LYP) calculation with the Gaussian 6-31 basis set (fraction of a minute calculation). A sample input file is here: Toluene_B3LYP-6-31G_geometry.
(5) Use the DFT-6-31 structure result to start a DFT B3LYP calculation with a larger basis set (e.g.,Dunnings augmented correlation-consistent valence-triple-zeta basis set. This basis is about as good as it gets, so this will be the final structure.) A sample input file is here: Toluene_B3LYP-accpVTZ_geometry.