Gamess (Quantum Chemistry software)

[brydustin]

Just curious if there are any advantages of specifying the symmetry of a molecule when trying to optimize geometry/energy using Gamess. I previously used Gaussian (which tells you the symmetry (if your initial guess was sufficient) when the calculation is complete). But really is there any numerical advantage? Can the program "cut" the molecule in half (if for example the molecule was symmetric with respect to reflection), and just optimize that one half (quicker?). Personally, I don't like forcing symmetry in my calculations because the output only shows half the molecule, but am curious if there is any advantage to using it? thanks all...

 

[DrClaude]

The point of using symmetry is indeed to reduce the number of calculations used, as the symmetry effectively reduces the number of degrees of freedom.