I am not sure I understand the question. Which elements are you talking about and why this is related to the band structure calculation of single and double layer materials? In most cases, you can build a single layer or multilayer system from the corresponding 3D layered material. The band structure is then calculated in the same way as for 3D materials, but you just have to use a single k-point (e.g., Gamma point) in the out-of-plane direction.