Educational practice problems/systems/reactions in computational chemistry I am not sure if this question is suitable for Chemistry SE, but I think fairly objective answers can be given, and not just I will benefit from them



I have almost completed the first year of a MSc program in theoretical (and computational) chemistry, and have gone from knowing absolutely nothing about computational chemistry, to having heard of some of the stuff I need to master. I just took the step of installing GAMESS on my personal computer, and I intend to start doing test calculations on my own.

While courses provide theoretical foundations, my experiences are that actual computations are quite limited. I took the initiative to engage in a student research project which started February this year, and during this time I have gained a lot of practical experience with calculations (exploring the PES, finding and optimizing transition state structures, calculating MEP's, looking at molecular orbitals). And to me this kind of experience is extremely valuable.

So I would like to practice with well-studied systems/reactions/whatever. In short, I want a diverse set of systems, some of which may require "manual labour" (e.g. CASSCF). With well-known systems I can find experimental and theoretical values to compare with, and likely also discussions about how certain methods perform for each system. These systems should be small enough so that they can be comfortably run on a Macbook Pro (2,9 GHz Intel Core i7, 8GB RAM, SSD) without taking too long.

So question basically is this: What is a good set of educational systems/reactions, suitable for an interested student in computational chemistry?
There's a free software quantum chemistry package called Psi4. If you're a GNU/Linux user, under Ubuntu or any Debian-based distro, you can install it with a simple terminal command.

sudo apt-get install psi4


They have a well documented site, including a section dedicated to education with simple projects and friendly message boards. As of today, they list the following projects in their education section:


What is the radius of an atom?
What makes a molecule polar or non-polar?
How do we calculate the most accurate energies for a boron atom?
Can we visually predict binding energies?
When does water become $\ce{OH + H}$? A study in molecular orbitals.
What happens to the orbitals as a one-dimensional box gets longer? A study in molecular orbitals.
Is $\ce{C3H+}$ present in the Horsehead nebula?
What is symmetry in chemistry?


The version available in Ubuntu repository is functional, but quite outdated, 1.1.5, as of Mar 2020. If one is serious about learning it, my advice is to download it directlly from their site. For me the only issue with it is that Avogadro, my output viewer of choice, seemingly doesn't provide native support to view Psi4 output files. But I count that as a missing feature in Avogadro, not Psi4.