New Answer to 80-Year-Old Question Makes Computer Modeling 100,000 Times Faster

PopSci ^ | 2-26-2010 | Jeremy Hsu

[grey_whiskers]

A new formula allows computers to simulate how new materials behave up to 100,000 times faster than previously possible, and could drastically speed up innovation relating to electronic devices and energy-efficient cars. Princeton engineers came up with the model based on an 80-year-old quantum physics puzzle.

Llewellyn Hilleth Thomas and Nobel laureate Enrico Fermi first theorized in 1927 that they could calculate the energy of electrons in motion based on how electrons are distributed in a material. Knowing that kinetic energy of electrons in a material helps researchers understand the structure and properties of new materials, as well as how they might respond to physical stress.

But the Thomas-Fermi equation was based on a theoretical gas with electrons distributed evenly, and so it could not work for imperfect real materials.

[dalereed]

What the hell is NES?

[Future Snake Eater]

That would be the Nintendo Entertainment System.

[count-your-change]

I would but it gets technical where the dead fish and umbrellas come in.

[dalereed]

I have no ides what that is.

[William Tell]

votemout said: "can someone explain this in public school english?"

Here's the key statement in the article: "Important properties are actually determined by the flaws,..."

Many useful devices, like those found in computer circuits, are made from crystalline materials like silicon. The silicon atoms are arranged in a predictable, repeating pattern.

The equations describing how electons behave in a pure silicon crystal are fairly well understood, but the equations apply to a crystal that is infinite in extent.

Real crystals have edges and boundaries where the repeating pattern of the silicon crystal is interrupted. The silicon atoms in these boundary areas are not positioned exactly as they would be if they weren't near the edge of the crystal.

Electrons that get near the edges of the crystal are able to undergo changes in energy that don't occur in the interior of the crystal.

An analogy might be to consider how boats behave while floating in a lake. Every prediction about such boats would be worthless if the boats always had small leaks that permitted water to flood the boat and sink it.

The behavior of electrons at the edges of silicon crystals can be similar. The electrons can "leak" from one energy level to another in a way that cannot occur in the interior of the crystal. When electrons have leaked, they are replaced by other electrons from the interior of the crystal, and then those replacement electrons leak. The net result is a "current" of electrons that dominates the behavior of the entire crystal.

The extremely tiny flow of electrons that happens in the interior of the crystal is completely swamped by the much larger currents that exist at the edges.

The significance of the article is that an improved method for calculating crystal behavior has been developed which permits larger models of real crystals to be modelled, resulting in more accurate predictions of how real crystal devices might behave.

[votemout]

Thank you. Direct and clear. Do tell!

[SunkenCiv]

Llewellyn Hilleth Thomas and Nobel laureate Enrico Fermi first theorized in 1927 that they could calculate the energy of electrons in motion based on how electrons are distributed in a material. Knowing that kinetic energy of electrons in a material helps researchers understand the structure and properties of new materials, as well as how they might respond to physical stress.

Thomas first saw the chalkboard with the formula, and asked, "is this fer me?"

/rimshot

Thanks grey_whiskers.

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[Future Snake Eater]

Well, that further proves my point.

[grey_whiskers]

Thomas first saw the chalkboard with the formula, and asked, "is this fer me?"

He asked Werner Heisenberg, who was uncertain.

Cheers!

[RightOnline]

ANSYS, CD-Adapco, and others. I spent years in the supercomputing field. These sorts of modeling are done these days on Linux clusters (typically).

[RightOnline]

LOL............good one.

[Rocky]

Is that Schrodinger’s cat? I understand he’s been looking for her.

[BlueLancer]

"Is that Schrodinger’s cat? I understand he’s been looking for her."

... or not ...

[AFreeBird]

Remember the old Atari game console. You know, the one you hooked up to your TV on channel 3/4 and played Pong?

An NES is w-a-y better. As is a Sony Playstation 3. Very realistic graphics; think CGI in movies. And games, especially flight sims and tactical games, can be a very good, and very inexpensive training tool.

[dalereed]

“Remember the old Atari game console.”

No, never seen one.
In fact i’ve never seen a computer game.

[AFreeBird]

Wow. Okay. Well google the NES and playstation 3. It will bring you to speed, ‘old timer’. ;-/

[dalereed]

I have no interest in any kind of games.

I quit that crap by age 6!

[SunkenCiv]

He’s both looking for her, and not looking for her. It’s been complicated because the sciences are littered with cats.