Linked Questions

14
votes
4answers
4k views

Restricted open-shell versus unrestricted methods for open shell systems

Open-Shell systems (radicals and so on) can be modeled by single-determinant quantum chemical methods using unrestricted (u) or restricted open-shell (ro) methods (I am aware that single-determinant ...
11
votes
4answers
709 views

Stability of 4-pyridone vs 4-pyridinol

In kryptomerism assignment, there was a question to compare more stable tautomeric form between 4-pyridone (1) and 4-pyridinol (2): Answer: 4-pyridone. My friend gave two plausible reasons: $\ce{C=...
26
votes
3answers
2k views

A comprehensive list of theoretical approximations that are used in computational chemistry

I am having trouble recognizing all the approximations that are used in computational chemistry. I would like to start an answer list (similar as to the list of resources for learning chemistry) that ...
15
votes
2answers
2k views

How do I make 3d molecular graphics similar to those shown on Wikipedia?

I want to make 3d molecular graphics similar to those found on Wikipedia. In the page for benzene, you can see the structure looks like this: However, if I go to the interactive image as shown in ...
11
votes
2answers
689 views

Is the notion of orbitals different in theoretical chemistry?

I am just an average chemistry student that is currently exposed to theoretical chemistry. And I am seeing very puzzling things, such as 1p, 2f, 3g orbitals. In my attempt to reconcile this, I was ...
5
votes
2answers
101 views

Why are excess nuclei required to produce an NMR signal?

In NMR, an excess population of nuclei is required to produce a signal. If saturation is achieved (same number of nuclei in the α and β states) no net signal can be produced. A signal is produced when ...

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