I'm having some troubles understanding the units used in solid state physics paper. In the paper I read
$\Lambda a \sim 1$
where $\Lambda$ is a momentum cutoff and $a$ is the lattice spacing of a crystal. Questions:
1) What kind of units are customarily used in solid state physics scientific articles? Can I be confident that they are atomic units?
2) The aforementioned equation is not (strictly speaking) dimensionally correct. If this was particle physics, I would say that one could set the speed of light and the Planck constant to 1 and make the equation correct. However in a low energy treatment in solid state physics, I don't see the point in using the speed of light or the Planck constant, and making the physics of the system dependent upon these quantities.