New calculation methods to find atomic properties

By combining advanced mathematics with high-performance computing, scientists have developed a tool that allows them to calculate a fundamental property of most atoms on the periodic table to historic accuracy. The technique could also be used to determine a host of other atomic properties important in fields like nuclear medicine and astrophysics.

IANS| Last Updated: Jun 26, 2014, 20:10 PM IST

New York, June 26 (IANS) By combining advanced mathematics with high-performance computing, scientists have developed a tool that allows them to calculate a fundamental property of most atoms on the periodic table to historic accuracy. The technique could also be used to determine a host of other atomic properties important in fields like nuclear medicine and astrophysics.

National Institute of Standards and Technology`s James Sims and Indiana University`s Stanley Hagstrom have calculated the base energy levels for four electrons in the element beryllium.

Precise determination of the base energy - crucial for determining the amount necessary to raise an atom from its base energy level to any level higher - has great intrinsic value for fundamental atomic research.

The team`s technique has implications far broader than for a single element.

Sims said that the technique allowed the calculation of excitation states with eight-decimal accuracy, resulting in a remarkably smooth curve that they expected theoretically but were not sure they would attain in practice.
For the vast majority of the elements in the periodic table, the calculated results are a thousand times more accurate than previous values.

The results, according to Sims, suggest their method could enable computation of other atomic properties - electron affinity and ionisation potential, for example - that are important for nuclear medicine, astrophysics and other fields of atomic research.

A form of cancer treatment now under development called boron neutron capture therapy may benefit from these calculations, he said.
Sims first proposed in the late 1960s that such a quantum approach could be possible, but the complex calculations involved were beyond the reach of the world`s best computers.

Beryllium`s four electrons proved a new hurdle, but perhaps the last significant one.

Much of the difficulty stems from the fact that mutual repulsion among the electrons, combined with their attraction for the nucleus, creates a complex set of interacting forces that are at least time-consuming, if not practically impossible, to calculate.

The complexity grows with the addition of each new electron, but the team found a mathematical approach that can reduce an atom`s electron cloud to a group of problems, none of which are more complex than solving a four-electron system.