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The chosen structure and level of theory is not remotely close to a reasonable approximation. You are calculating an anion with charge -2, but there are no polarisation or diffuse functions in STO-3G. …

Disclaimer: This is not going to be an answer to the question. This is just a collection of thoughts on it, which hopefully helps to form a better understanding. First and foremost, and this should go …

This is deeper discussed in Rate Constant Units and Eyring Equation, but I am going to post a very short take-home message here. First, the three assumptions you have cited are not complete. They comp …

Beyond the educational value, Bent's rule has had significant impact on how we understand wave functions of molecules. It's simplicity is almost unique in the world of quantum chemistry; almost everyb …

In its guide to model antiferromagnetic couplig, Gaussian uses $\ce{Mn2O2(NH3)8}$ as a model compound.[1] It argues that manganese is in II oxidation high spin state; in other words, in both manganese …

Oxidation states are just numbers, a bookkeeping tool for chemistry. These hardly ever correspond to anything observable. Point in case: hypofluorous acid $\ce{HOF}$, see for example the oxidation sta …

Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically …

It is safe to say that there will always be intermolecular forces at play. At the time where you will consider these you should already have a good idea about the molecules involved in your system. Ba …

The exchange operator is not a operator by itself, it is only defined with the orbital it is working on: $% \newcommand{\ll}{\left\langle}\newcommand{\rr}{\right\rangle} \newcommand{\lb}{\left|}\newc …

I would use a slightly different approach than andselisk, based on the volume on your box, and that I don't think you can neglect the volume of your ammonia molecules. Given $V(\text{sol}) = \pu{17.57 …

Resonance is a remnant of valence bond theory, which is necessary because it is impossible to describe delocalised bonding within a localised bonding scheme. Resonance structures are not real. One Lew …

Yes, and no, and maybe. Oftentimes the sign of the Laplacian at the bond critical point in terms of the quantum theory of atoms in molecules (QTAIM) is taken as a measurement for the covalency of a b …

Yes in principle that is a correct approach, but you should be aware of a few pitfalls here and there. The basis set you chose for your optimisation might not be large enough. I assume you are not go …

I have said it a couple of times already on our site,[1] but I'm not getting tired of saying it again: Hybridisation always follows the (spatial) geometry of the molecule, never the other way arou …

No, there is no automation for this, and there should not be. Using compound jobs is unfortunately very common among computational chemists, but they should always be viewed critically. If you are us …