A Material Analysis of MoSe2

Molebdynum Diselenide, a Transition-Metal Dichalcogenide (TMDC) is a byproduct in the production of layered deposition of thin film solar panels. Because of this, we are interested in the bandgap of monolayer and multilatyer MoSe2 as well as its other properties with regards to solar panel materials. In this project, we discussed how we calculated these material properties by using the ab initio plane wave code Quantum Espresso and the ThreeBodyTB.jl package in Julia, and as well as some of the results we gathered.

Provided below is a little snippet from our code that I contributed to and we use this to convert our crystal coordinates (that are cartesian coordinates) to fractional coordinates so that we can simulate and make structures of crystals from the “ThreeBodyTB” package:

# Function to convert Cartesian coordinates to fractional coordinates
function cartesian_to_fractional(
    A::Matrix{Float64},
    cartesian_coords::Vector{Vector{Float64}}
) :: Matrix{Float64}
    # 1) Invert the lattice matrix
    A_inv = inv(A)
    
    # 2) Convert each Cartesian coordinate to fractional
    fractional_coords = [A_inv * v for v in cartesian_coords]
    
    # 3) Form a 2D matrix (rows = fractional coordinates)
    frac_matrix = hcat(fractional_coords...)'
    
    return frac_matrix
end

In the end, we want to make sure our calculations from the ThreeBodyTB package will match the literature values so we can release it to the public for use!