The following lengthy article, I think is very important. I have long
thought that the "replicator" used in the Star Trek space series was the
ultimate invention. The creation of matter by basic molecular
reconstruction solves that Starships food problem. On Earth, we may find
that a "replicator" technology might supply needed resource material we have
overused or perhaps even food that can be made as a manufactured product
based on mathematically knowing all the molecular compounds and developing
ways to combine them. What freedom that would bring - that each person
might have the "means of production" as defined in Hilaire Belloc's book The
Servile State - and perhaps more than just production, but also, the
creation of all necessary and luxury items a person could desire - made from
recombining at the molecular level. Is that a possibilitythat can be drawn
from this article below?
Respectfully,
Thomas Lunde
----------
>From: Mark Graffis <[EMAIL PROTECTED]>
>To: graffis-l <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
>Cc: Bob Sinclair <[EMAIL PROTECTED]>
>Subject: [graffis-l] The Virtual Alchemists
>Date: Tue, Jul 6, 1999, 3:15 PM
>
> From: Mark Graffis <[EMAIL PROTECTED]>
>
>
> TECHNOLOGY REVIEW
> MIT Bldg. W59-200 201 Vassar St. Cambridge, MA 02139 Tel
> 617-253-8250 Fax 617-258-5850 [EMAIL PROTECTED] CURRENT ISSUE
>
> July/August 1999
>
>
> After a decade of calculations, the first wave of materials
> designed from scratch on the computer are ready to be made and
> tested. On the horizon: new substrates for optics and electronics.
>
> By [16]David Voss
>
> photo The first thing you notice about Gerbrand Ceder's materials
> science lab at MIT is that there are no crucibles, no furnaces, no
> crystal-growing instruments. Instead, you find a row of
> high-resolution computer displays with grad students and postdocs
> tweaking code and constructing colorful 3-D images. It's in this
> room, quiet except for the hum of fans cooling the computer power,
> where new high-tech ceramics and electronic materials that have
> never been seen or made before are being forged. They are taking
> form "in virtuo"designed from scratch on the computer, distilled
> out of the basic laws of physics.
>
> The next thing you're likely to notice is how young Ceder is. Quick
> to laugh but intensely passionate in explaining his work, the
> 33-year-old associate professor is one of a new breed of materials
> researchers, trained in traditional processing techniques, who have
> turned to discovering materials using computers. The dream is
> simple: Replace the age-old practice of finding new substances by
> trial and error, with calculations based on the laws of quantum
> mechanics that predict the properties of materials before you make
> them.
>
> You can, in theory at least, design metals, semiconductors and
> ceramics atom by atom, adjusting the structure as you go to achieve
> desired effects. That should make it possible to come up with, say,
> a new composition for an electronic material much faster. Even more
> important, tinkering with atomic structure on a computer makes it
> possible to invent classes of materials that defy the instincts of
> the trial-and-error traditionalists.
>
> It's an idea that has been kicking around for at least a decade.
> But with the explosion in accessible computer power, as well as the
> development of better software and theories, it's becoming a
> reality. Last year, Ceder and his collaborators at MIT synthesized
> one of the first materials that had actually been predicted on a
> computer before it existed. This new aluminum oxide is a cheap and
> efficient electrode for batteries. And while it may or may not lead
> to a better, lighter rechargeable battery, the success of Ceder's
> groupand related work at a handful of other labsis proving that
> useful materials can be designed from the basic laws of physics.
>
> Designing from first principles represents a whole new way of doing
> materials science, a discipline that Ceder describes as "a
> collection of facts with some brilliant insights thrown in." It's a
> transformation he's been aiming at since his undergraduate days in
> the late 1980s at UniversitÈ Catholique de Louvain in Belgium. "My
> background is heat and beat metallurgy," he explains. "But I always
> thought there should be more to it, some way to calculate things
> using all the great physics of quantum mechanics."
>
> Getting there, however, won't be easy. Scientists have known for
> decades that, according to the rules of quantum mechanics, if you
> could detail the position of the electrons swarming around atoms,
> you could then calculate physical properties of the material. Yet
> the sheer difficulty of carrying out these calculations has made
> the task seem hopeless. The computations are hard for even one
> molecule, but for the huge numbers of atoms that make up even the
> smallest chunk of a solid material, the chore is truly
> intimidating.
>
> In the search for new vaccines and drugs, where computer-aided
> design has taken off, progress has been achieved precisely because
> the designers have been able to skip the influence of particular
> electrons, along with the rigorous quantum calculations. But
> inorganic materials are tougher. The properties of metals, alloys,
> semiconductors and oxides result from a vast sea of interconnected
> atoms and electrons. "With metals and ceramics, we really need to
> include the electrons as active players," explains Erich Wimmer of
> Molecular Simulation, a software company that markets molecular and
> materials computer modeling programs. "And that means we need
> quantum mechanical methods."
>
> The linchpin of quantum mechanics is the Schr–dinger Equation,
> which describes how electrons arrange themselves around atoms and
> how atoms share electrons to form chemical bonds. The Schr–dinger
> Equation generates a "wave function" giving the probability that an
> electron will be at a given location at a given time. What makes it
> so powerful is that the wave function can reveal physical
> properties of the system: energy, optical absorption, conductivity.
> If done right, you insert the atomic masses and crystal structure,
> and out pops the physical properties of the material. The
> calculations are called "first principles" or "ab initio" because
> you start with the most fundamental information about the atoms and
> use the most basic rules of physics. The price researchers pay for
> this ability is that the Schr–dinger Equation requires immense
> computer power to solve, even for simple atomic structures.
>
> The Right Stuff
>
> Eight years ago, ceder showed up at MIT (he received his PhD from
> the University of California, Berkeley, in 1991) as a newly minted
> professor ready to give the Schr–dinger Equation a try on one of
> materials science's most pressing problems: better batteries.
> Today's frenzy for cell phones and laptops has driven the quest for
> lighter and more powerful storage materials. Lithium cobalt oxide
> is the electrode of choice for lightweight high-power applications,
> particularly products like cell phones. But lithium is expensiveand
> cobalt is even pricier. The costs can be passed on in high-tech
> gadgets like cell phones and laptops but for other uses, such as
> powering electric cars, it's prohibitive.
>
> Several of Ceder's MIT colleagues began working on an improved
> battery. But it was obvious they needed better, cheaper oxide
> materials to serve as the electrodes. The traditional materials
> science strategy would have called for mixing up a batch of an
> oxide and then adding and subtracting components a little at a
> time. But there are almost unlimited combinations of ingredients
> you can put inand every ingredient affects every other ingredient.
> "Every time you make a chemical change, lots of other things get
> altered too," explains Ceder. "There may be structural changes, and
> who knows what else."
>
> Ceder attacked the problem by creating the samples and testing them
> not on the bench, but on the computer. "The advantage is that you
> have full control over what you do," he says. "If I take a crystal,
> and add a little bit of some element, I can see exactly how the
> electrical conductivity will change." Systematically changing the
> electrode composition, Ceder used his software code to calculate
> the effects on battery voltage. By replacing the cobalt with
> titanium, or vanadium, could they get a peppier energy cell?
>
> What they found was surprising. The voltage didn't depend strongly
> on the cobalt. In fact, the voltage was highest if all the cobalt
> were replaced with aluminum. This was entirely unexpected, Ceder
> says, because aluminum had been thought to be a nonplayer in
> battery oxides. But there was a hitch. Lithium aluminum oxide is an
> insulator. So even though the numbers showed the voltage would be
> at a peak, there would be no way to run a current through it.
> Calculations indicated, however, that a mixture of cobalt and
> aluminum might just do the job: enough cobalt to keep the electrode
> conductive, and aluminum to replace the rest.
>
> That, at least, is what the computer showed. Someone still had to
> make the stuff. Enlisting the help of MIT ceramists, Ceder and his
> colleagues developed methods to synthesize the predicted
> cobalt-aluminum electrodesmaterials that had never been made
> before. It turns out that, in fact, the mixture of cobalt/aluminum
> gives a higher battery voltage than cobalt alone. At the same time,
> the aluminum lowered the overall weight of the material, so that
> the energy densityanother important figure for a good batterywent
> up, and the projected cost of the material went down.
>
> Arranged Marriage
>
> Don't expect to find cobalt-aluminum electrodes in a battery
> anytime soon, however. Although the new battery material is
> superior in voltage and costs to conventional electrodes, the
> conservatism of the power-storage business means that it's not
> likely to be commercialized in the near future. Still, the success
> of Ceder's group marks a significant advance because it means a
> material has been designed on the computer and found actually to
> have the predicted qualities.
>
> Scientists are far from being able to plunk themselves down at a
> keyboard, tap in some desired properties, and have a new substance
> pop out. Ceder points out that electronic and optical properties
> are relatively amenable to calculation, whereas other important
> characteristics, like hardness or corrosion resistance, are more
> difficult to compute. Those properties, for one thing, depend on
> events occurring over a wide range of size and time scales (see
> sidebar: "[17]Cracking a Tough Problem"). "There are still a lot of
> problems you can't address by these methods," he says.
>
> For now, though, the rewards of finding novel electronic and
> optical materials are more than enough to keep top materials
> researchers interested. A few dozen meters from Ceder's lab,
> another MIT group, headed by theoretical physicist John
> Joannopoulos, believes it has solved one of the toughest puzzles in
> semiconductor researchproviding a material bridge between
> electronics and optics.
>
> Such a connection could make it possible to build silicon-based
> semiconductors that are able to carry out optical-based operations.
> But getting there means mating silicon with stuff that has
> favorable optical properties. And from a materials science point of
> view, there is a major hurdle: Optical and electronic materials
> tend to be incompatible. "Silicon is great for making electronic
> circuits, but it has lousy optical properties," says Joannopoulos.
> "Things like gallium arsenide that have good optical properties
> hate to be stuck on top of silicon."
>
> The reason is that the best optical materials for the part of the
> spectrum that industry is interested inaround wavelengths of 1.5
> micrometershave atomic spacings that don't match silicon. So, if
> you grow gallium arsenide on silicon, the mismatch causes havoc in
> the interfacestress, strain and defects galore. This situation
> presented a unique opportunity for design-from-first-principles,
> says Joannopoulos. "We asked ourselves, could we take the
> specifications and design a material to meet them?"
>
> The answer: yes. The timeframe: a decade of difficult calculations.
> The solution involved a recipe for putting layer after layer of
> different elements down on a silicon surface, each layer from a
> different group in the periodic table. If the approach had been
> tried experimentally, it would have involved an almost unlimited
> number of combinations, and each batch would have to have been
> synthesized and tested. Instead, Joannopoulos and his co-workers
> did extensive ab initio calculations on the computer to nail down
> the optical properties and the atomic spacing.
>
> This year, grad student Tairan Wang finally hit on a layering
> scheme that created a new material with the right structure to join
> smoothly with the silicon surface and still act as an optical
> material. By putting down arsenic, zinc, silicon and phosphorus in
> just the right orderon the computer, of coursehe was able to hit
> the target. "The main thing is we've identified a class of
> compounds," says Joannopoulos, "so if this particular one is
> difficult to fabricate, we can try another that will also meet the
> specifications."
>
> Once you've cleverly designed something on a computer, you still
> have to find a willing experimentalist to make the stuff. In the
> case of Joannopoulos' new optoelectronic material, the problem is
> that nobody has a synthesis setup that can spray the atomically
> precise layers of the four different elements. But after a decade
> of struggling to find the right structure, Joannopoulos isn't
> worried. He says a couple of labs are interested. And he expects to
> get to work soon on actually making the material.
>
> Playing God
>
> photo Whatever the eventual value of these computationally designed
> materials, the work is unquestionably opening up researchers'
> imaginations. Like Ceder, Efthimios Kaxiras is one of the new
> generation of materials researchers more skilled in computational
> physics than in firing up a laboratory kiln. An MIT graduate and
> former student of Joannopoulos, Kaxiras is now an associate
> professor of physics at Harvard University, where he is dreaming up
> materials that no one has ever seen.
>
> In one such research project, Kaxiras is envisioning tiny clusters
> of silicon atoms that could perform useful tasks. "When you take a
> few hundred atoms of something, it behaves very differently than
> the bulk material," he says. In thinking about how silicon atoms
> bond, Kaxiras came up with a new structure containing a mere 45
> atoms. "These 45 silicon atoms form two mirror-image structures,"
> he explains. "And if you could figure out how to induce one to
> change into the other, you could have a tiny switch."
>
> Clearly a switch only 45 atoms big would make circuit designers
> delirious. By comparison, there are hundreds of thousands of atoms
> in each of today's smallest circuit elements. But the silicon
> clusters remain very much in the realm of the virtual imagination.
> Says Kaxiras, "Nothing is known about these structures. I came up
> with them by thinking of the possibilities, and then I fed the
> structures into the computer to learn more about their stability
> and physical properties." Kaxiras says more experimental work is
> needed to know even whether these structures actually can be
> created.
>
> "It's really hard playing God," says Joannopoulos of his 10-year
> quest for novel optoelectronic materials. Indeed, designing new
> materials from scratch using the basic laws of physics is, in many
> ways, more demanding than the trial-and-error approach to finding
> substances. It requires unconventional thinking about materials and
> the skillful use of a computational tool kit that is only now being
> developed. But if this new breed of researchers succeed, they could
> be on the verge of creating a whole new materials world.
>
> David Voss is a freelance writer and former senior editor of
> Science magazine. He wrote about nanotechnology in the March/April
> issue.
>
> 23. http://www.techreview.com/currnt.htm
>
>
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