Quantum-based material’s calculations are a simulation activity, not a theoretical activity.
Material theory is governed by the known rules of quantum mechanics. Using these rules in a colputer simulation is not theoretical physics. Because in theoretical physics we are looking to formalize new rules.
People often think it is theory but that’s due to the bad name QM has. It’s impossible to understand many people say, this causes them to think scientists and engineers don’t know how to use the theory, which is plain wrong.