# Number of electrons per cell

I aim to do a HF-like calculation on a 2D graphene layer. What is the number of electrons per cell?

Edit: There are six carbon atoms per cell.

• +1 but do you mean "unit cell"? How many carbon atoms do you have in each "cell"? Dec 5, 2023 at 20:42
• If there's 6 carbon atoms per cell, and each carbon atom has 6 electrons, then why wouldn't the number of electrons per cell be 36? Dec 5, 2023 at 21:02
• Since each cell is an hexagon, each carbon is in 3 cells. So each cell has $6/3=2$ electrons per cell per atom, so why wouldnt be the number of electron per cell be 12? Also is the number of electron per cell the same if the core electrons are frozen?
– mle
Dec 6, 2023 at 9:10
• Frozen core approximations are usually invoked for electron correlation calculations, not for HF calculations. You make a good point about each cell sharing some of the carbon atoms though. Dec 6, 2023 at 13:43

I did some searching and found that a unit cell of graphene contains two atoms, with each each hexagonal mer consisting of 6 atoms of carbon.

https://chemistry.stackexchange.com/questions/69346/a-unit-cell-for-graphene

It is noted that this is for neutral graphene rather than GO, rGO, Bilayer, et al.

(graphene) AND (Hartree-Fock OR HF) AND (unit cell) AND (Density Functional Theory OR DFT) AND PySCF