A celebration of molecules imagined before they were seen.
In brief:
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Quantum chemistry isn’t just explaining—it’s predicting.
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From dyes to DNA, theory often shines before the first test tube.
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Simulations and experiments go hand in hand in modern chemistry.
Can you guess what connects solar cell dyes, spintronics, and antimatter? They were all understood—sometimes even discovered—on a computer screen before any lab experiment confirmed them. That’s not science fiction. That’s computational chemistry today.
In a special issue for the International Year of Quantum Science and Technology, I take us on a tour of twenty striking case studies where theory made predictions that experiments later verified.
Milestones in the development of theoretical chemistry (green circles) and its computational algorithmic and software expressions (red boxes) in a timeline with the key quantum mechanical developments for the field (black circles) and computational science infrastructure achievements (purple boxes). A profound reshaping of the field is occurring due to data science advances (orange boxes). It’s still unclear, but future advances can emerge from quantum computing (blue boxes).
This isn’t just number-crunching. Predicting a new dye for solar cells or identifying an unusual bond in a positron-laced molecule isn’t like rolling dice. It’s about translating quantum mechanics into code, then using that code to explore vast chemical spaces—sometimes millions of possibilities. That’s how a team identified WM3, a dye with record-breaking efficiency, months before they ever synthesized it.
Theory doesn’t always get the spotlight in chemistry, but it often gets there first. Think of carbon atoms tunneling like ghosts through reaction barriers. Or peptides folding into hydrogels based purely on simulations. Or discovering that water molecules at the air interface wobble in a strange way—something theory predicted years before it was spotted by laser spectroscopy.
Some of these predictions may seem lucky. Most are not. They come from tough equations, clever algorithms, and deep trust in the laws of quantum physics. And they remind us that chemistry isn’t just about flasks and fumes anymore. It’s also about data, models, and fearless imagination.
Of course, theory alone isn’t enough. The best science happens when theory and experiment talk to each other—sometimes argue, always inspire. And perhaps the best advice from this review is a simple one: if you’re a theoretical chemist, don’t wait for the experiment. Be bold. Predict something.
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Reference
[1] M. Barbatti, When theory came first: a review of theoretical chemical predictions ahead of experiments, Pure Appl. Chem. (2025). 10.1515/pac-2025-0455
