The 2013 Nobel Prize for Chemistry has been jointly awarded to Martin Karplus, Michael Levitt and Arieh Warshel.
They received the award in recognition of their work on "developing multiscale models for complex chemical systems".
Computer models are used today to understand and predict chemical processes and have replaced the plastic balls and sticks that chemists previously used to model molecules.
According to the Royal Swedish Academy of Sciences, the three men laid the foundation for these powerful programmes that are used to understand and predict chemical processes.
The academy described the work of the three US-based scientists as ground-breaking, because they made the classical physics of Isaac Newton work alongside quantum physics, opening up new opportunities to chemists who previously could only use one or the other.
Classical physics, for example, did allow simple modelling of big molecules, but did not offer a way to simulate chemical reactions, which could only be done on small molecules, requiring enormous computing power.
The scientists came up with a method that used the best of both classical and quantum physics.
For example, in simulations of how a drug couples to its target protein in the body, the computer performs quantum theoretical calculations on those atoms in the target protein that interact with the drug.
The rest of the large protein is simulated using less demanding classical physics.