@ZachWeinersmith My husband does quantum mechanical computations of materials, in close collaboration with experimental physicists and chemists. They can tell him things like: there is about X% of element Y in there and we baked it/annealed it/... for n hours. That's a long way from a crystal structure, and yet a good guess for that is needed as a starting point, otherwise the computations get stuck in a local energy minimum.
As far as I can tell, quantum computers wouldn't help much with that.