Some useful links for people dealing with quantum chemistry

At this page we are collecting links we find useful in our own research work.

1) Gaussian Error Messages

https://www.ace-net.ca/wiki/Gaussian_Error_Messages

Here 26 types of Gaussian error messages are explained (e.g., memory allocation problems, change in point group or standard orientation, convergence failure, etc.).

2) Practical Advice for Quantum Chemistry Computations, by C. David Sherrill.

http://www.chemcraftprog.com/tmp/quantum-practical.pdf

Here many simple hints are provided:

 - The choice of basis set;

 - The choice of ab initio/DFT methods for different tasks.

The author writes that standard HF, semiempirical, and DFT techniques are not appropriate for van der Waals complexes or systems dominated by London dispersion forces. However, Ref. reported that for the compounds under investigation the B3LYP-gCP-D3/6-31G* method could correctly compute London dispersion effects (and it does not have the basis set superposition error);

 - Hints on the problem of SCF convergence;

 - Common hints on imaginary frequencies and saddle points;

 - Hints on optimization with symmetry.