Quantum computing goes beyond H and He
STU BORMAN · C&EN Global Enterprise · 2017
Quantum computers could be the future of computational chemistry if they can calculate properties of molecules that conventional digital computers can’t handle. Today’s quantum systems are a long way from reaching that goal. But a quantum computer at IBM just passed a milestone: It performed the first calculations involving molecules containing more than just hydrogen and helium. Digital computers crunch numbers to describe properties such as a molecule’s ground-state energy by using the Schrödinger equation to calculate mathematical parameters called wave functions. However, digital computers can solve such problems exactly only for elementary molecules because of the great complexity of the many interactions of the multiple subatomic particles found in larger compounds. With digital computers, “exact solutions rapidly become unfeasible, even for the fastest computers working over the entire lifetime of the universe,” says theoretical chemist Donald Truhlar of the University of Minnesota, who was not involved in the new