Spin-dependent band gap calculations

[Sebas_Na_Osle]

Dear colleagues,
I am trying to deal with quantum-chemical calculations of metal-containing coordination polymers, and I have a question which turned out to be difficult to me:

If a system includes copper atoms, which implies that it has 'unpaired' electron, how to describe a band gap in this case? I mean we can estimate two different band gaps for 'spin-up' and 'spin-down' channels, but what should we take as a reference to compare with experimental data?

If you can advise me some literature on this, it would be also great.

Thank you

 

[eljose79]

for your question, colleague. This is indeed a challenging problem, and one that has been a topic of research in the field of quantum chemistry for many years. The presence of unpaired electrons in metal-containing coordination polymers adds another layer of complexity to the calculation of band gaps.

To answer your question, we first need to understand what exactly a band gap is in the context of quantum chemistry. In simple terms, a band gap is the energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a molecule or material. In a system with unpaired electrons, this energy difference can vary depending on the spin state of the electrons. Therefore, it is important to consider both the spin-up and spin-down channels when calculating the band gap.

In terms of comparing with experimental data, it is common practice to use the average of the spin-up and spin-down band gaps as a reference. This is because in most cases, the overall electronic structure of the system is a combination of both spin states. However, it is also important to consider the individual spin states and their contributions to the overall band gap.

As for literature on this topic, I would recommend looking into papers on density functional theory (DFT) calculations of metal-containing coordination polymers. DFT is a commonly used method for calculating band gaps in these types of systems. Some specific papers that may be helpful are "Electronic structure and properties of metal-containing coordination polymers" by J. M. Soler and "Spin-polarized density functional theory calculations of magnetic coordination polymers" by P. B. Littlewood.

I hope this helps in your research. Best of luck!