Three scientists won the Nobel Prize for Chemistry on Wednesday for developing computer models to simulate chemical processes, providing a revolutionary tool for drug designers and engineers.

Martin Karplus, a US-Austrian citizen, Michael Levitt, a US-British citizen, and Arieh Warshel of the US and Israel were honoured "for the development of multiscale models for complex chemical systems," the Nobel jury said.

The three were being recognised for "taking the experiment to cyberspace," it added.

Chemists all over the world simulate complex experiments on their computers thanks to work by the trio that dates back to the 1970s, the Royal Swedish Academy of Sciences said in a statement.

"I was doing work before my post doc when I was 20 years old to write a computer programme. I guess I wrote a pretty good programme," Levitt, now 66, told AFP by telephone from his California home.

He said that it was "essentially" this programme that lay at the core of Wednesday's Nobel prize, and people benefitted from it to this day.

"I was speaking to a doctoral student yesterday and he was able to do a calculation that used to take two hours and now takes a 100th of a second," Levitt said. "It makes a huge difference!"

The Nobel jury said the tool is "universal", helping pharmaceutical engineers to design new drugs or engineers to make cleaner energy sources or smarter manufactured products.

The three combined classical physics with quantum physics -- two previously rival worlds -- in computer models designed to predict chemical reactions.

Such reactions can take place, for instance, between industrial chemicals or in biological functions, when an enzyme cuts a protein, a virus penetrates a cell or or a cell divides.

The processes can happen in a fraction of a millisecond, defeating conventional algorithms that try to map them step by step.

By including quantum physics in the computational mix, the number of permutations for calculation rises hugely, as they incorporate the possibility that an atom is in one of several of the famously fickle quantum states at any time in the processes.

This also requires enormous computer power to crunch the data.

"The computer models that have been developed by the Nobel laureates in chemistry 2013 are powerful tools," the academy observed.

"Exactly how far they can advance our knowledge is for the future to decide."

Computer models had also radically changed the ways chemists do their work, the academy observed.

"Today the computer is just as important a tool for chemists as the test tube," it said.

Karplus, 83, works at the University of Strasbourg in eastern France and Harvard University; Levitt at Stanford University; and Warshel, 72, at the University of Southern California.

The Academy of Sciences said Levitt has described his dream of simulating a living organism on a molecular level as a "tantalising thought."

The trio will share the prize sum of eight million Swedish kronor ($1.25 million, 925,000 euros), reduced because of the economic crisis last year from the 10 million kronor awarded since 2001.

In line with tradition, the laureates will receive their prize at a formal ceremony in Stockholm on December 10, the anniversary of prize founder Alfred Nobel's death in 1896.

Last year, the honour went to Robert Lefkowitz and Brian Kobilka of the United States for identifying a class of cell receptor, yielding vital insights into how the body functions on the molecular scale.