Theorists Close In on Improved Atomic Property Predictions

Jan 13, 2010

(PhysOrg.com) -- Scientists at the National Institute of Standards and Technology and Indiana University have determined the most accurate values ever for a fundamental property of the element lithium using a novel approach that may permit scientists to do the same for other atoms in the periodic table.

NIST’s James Sims and IU’s Stanley Hagstrom have calculated four excitation energies for the atom approximately 100 times more accurately than any previous calculations or experimental measurements. Precise determination of excitation energy—the amount necessary to raise an atom from a base energy level to the next higher—has intrinsic value for fundamental research into atomic behavior, but the success of the method the team employed has implications that go beyond lithium alone.

The theorists have overcome major computational and conceptual hurdles that for decades have prevented scientists from using to predict electron excitation energies from first principles. Sims first proposed in the late 1960s that such a quantum approach could be possible, but its application to anything more than two electrons required a fiendishly difficult set of calculations that, until recently, was beyond the capacity of even the world’s fastest computers. In 2006 the team used a novel combination of algorithms, extended precision computing and the increase in power brought about by parallel computing to calculate the most accurate values ever for a simple, two-electron .

By making improvements to those algorithms, Sims and Hagstrom now have been able to apply their approach to the significantly more difficult problem of lithium, which has three electrons. Much of the original difficulty with their method stems from the fact that in with more than one electron the mutually among these tiny introduces complications that make calculations extremely time-consuming, if not practically impossible.

Sims says that while the lithium calculation is valuable in itself, the deeper import of refining their method is that it should enable the calculation of excitation energies for beryllium, which has four electrons. In turn, this next achievement should enable theorists to predict with greater accuracy values for all of the remaining elements in the second row of the periodic table, from beryllium to neon, and potentially the rest of the as well. “The mathematical troubles we have with multiple electrons can all be reduced to problems with four electrons,” says Sims, a quantum chemist in the mathematics and computational sciences division. “Once we’ve tackled that, the mathematics for other elements is not any more difficult inherently—there’s just more number-crunching involved.”

To obtain their results, the researchers used 32 parallel processors in a NIST computer cluster, where they are currently working on the calculations for beryllium.

High precision determinations of excitation energies are of interest to scientists and engineers who characterize and model all types of gaseous systems, including plasmas and planetary atmospheres. Other application areas include astrophysics and health physics.

Explore further: The unifying framework of symmetry reveals properties of a broad range of physical systems

More information: J.S. Sims and S.A. Hagstrom. Hylleraas-configuration-interaction study of the 2 2S ground state of neutral lithium and the first five excited 2S states. Physical Review A, Nov. 19 2009, DOI:10.1103/PhysRevA.80.052507

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User comments : 6

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mayan
1 / 5 (3) Jan 14, 2010
You will Shun by some space metals that do exotic things,singularity existing in metals, ancient bones,old wood that attracts cereals like r_ "iice" (to prevent search engines from accessing) etc, these objects pull the r_ "iice" and turn them them black & burn them, they attract flame, they transfer power to "ccooppper" wire and this in turn attracts the cereal R_ "iice". The main principle to test behind this is any non metallic hydride is being pulled by these exotic objects, ie they suck the hydrogen . They neutralize electronics.

Their power is increased 1000's of times in a German lab, these can stop any air vehicle by gravity beams etc.
mayan
1 / 5 (3) Jan 14, 2010
some text too will be there in 1970's books on "Rare Earth Metal Applications"
mayan
Jan 14, 2010
This comment has been removed by a moderator.
Rohitasch
Jan 14, 2010
This comment has been removed by a moderator.
mayan
1 / 5 (2) Jan 14, 2010
See the below post by mayan for utube proofs http://www.physor...034.html
joefarah
1 / 5 (1) Jan 14, 2010
Wait a minute... didn't I just read an article that said how a quantum computer was used to precisely identify the excitation energy of a H2 electron, without all of the difficult math?
Olen_Ahkcre
not rated yet Jan 14, 2010
Wait a minute... didn't I just read an article that said how a quantum computer was used to precisely identify the excitation energy of a H2 electron, without all of the difficult math?


You only think you did, otherwise find the article and get back to us with a link, OK?
nevermark
1 / 5 (1) Jan 14, 2010
Here is the link to Quantom Computer computes exact energy of molecular Hydrogen:

http://www.physor...030.html

My guess is a traditional computing breakthrough as described here will be much easier to scale up than a quantum calculation. At least for many years.