We have excellent approximations of the full quantum chemistry that work really well, e.g. DFT. It's the gold standard for chemistry today. But these edge cases, although rare, do show up. They have a nasty tendency of showing up in biology especially, where reactions often happen on a knife's edge of the energy landscape, for efficiency reasons.
Chemists are interested in quantum simulation because it would be fully accurate and be an actual substitute for ground-truth experiment. With these approximations, you still wouldn't know if what you're simulating matches reality.
Chemists are interested in quantum simulation because it would be fully accurate and be an actual substitute for ground-truth experiment. With these approximations, you still wouldn't know if what you're simulating matches reality.