Navigation Links
New technique allows simulation of noncrystalline materials

CAMBRIDGE, Mass. -- A multidisciplinary team of researchers at MIT and in Spain has found a new mathematical approach to simulating the electronic behavior of noncrystalline materials, which may eventually play an important part in new devices including solar cells, organic LED lights and printable, flexible electronic circuits.

The new method uses a mathematical technique that has not previously been applied in physics or chemistry. Even though the method uses approximations rather than exact solutions, the resulting predictions turn out to match the actual electronic properties of noncrystalline materials with great precision, the researchers say. The research is being reported in the journal Physical Review Letters, published June 29.

Jiahao Chen, a postdoc in MIT's Department of Chemistry and lead author of the report, says that finding this novel approach to simulating the electronic properties of "disordered materials" those that lack an orderly crystal structure involved a team of physicists, chemists, mathematicians at MIT and a computer scientist at the Universidad Autnoma de Madrid. The work was funded by a grant from the National Science Foundation aimed specifically at fostering interdisciplinary research.

The project used a mathematical concept known as free probability applied to random matrices previously considered an abstraction with no known real-world applications that the team found could be used as a step toward solving difficult problems in physics and chemistry. "Random-matrix theory allows us to understand how disorder in a material affects its electrical properties," Chen says.

Typically, figuring out the electronic properties of materials from first principles requires calculating certain properties of matrices arrays of numbers arranged in columns and rows. The numbers in the matrix represent the energies of electrons and the interactions between electrons, which arise from the way molecules are arranged in the material.

To determine how physical changes, such as shifting temperatures or adding impurities, will affect such materials would normally require varying each number in the matrix, and then calculating how this changes the properties of the matrix. With disordered materials, where the values of the numbers in the matrix are not precisely known to begin with, this is a very difficult mathematical problem to solve. But, Chen explains, "Random-matrix theory gives a way to short-circuit all that," using a probability distribution instead of deriving all the precise values.

The new method makes it possible to translate basic information about the amount of disorder in the molecular structure of a material that is, just how messy its molecules are into a prediction of its electrical properties.

"There is a lot of interest in how organic semiconductors can be used to make solar cells" as a possible lower-cost alternative to silicon solar cells, Chen says. In some types of these devices, "all the molecules, instead of being perfectly ordered, are all jumbled up." These disordered materials are very difficult to model mathematically, but this new method could be a useful step in that direction, he says.

Essentially, what the method developed by Chen and his colleagues does is take a matrix problem that is too complex to solve easily by traditional mathematical methods and "approximates it with a combination of two matrices whose properties can be calculated easily," thus sidestepping the complex calculations that would be required to solve the original problem, he explains.

Amazingly, the researchers found that their method, although it yields an approximation instead of the real solution, turns out to be highly accurate. When the approximation is plotted on a graph along with the exact solution, "you couldn't tell the difference with the naked eye," Chen says.

While mathematicians have used such methods in the abstract, "to our knowledge, this is the first application of this theory to chemistry," Chen says. "It's been very much in the domain of pure math, but we're starting to find real applications. It's exciting for the mathematicians as well."

The incredible accuracy of the method, which uses a technique called free convolution, led the team to investigate why it was so accurate, which has led in turn to new mathematical discoveries in free probability theory. The method derived for estimating the amount of deviation between the precise calculation and the approximation is new, Chen says, "driven by our questions" for the mathematicians on the team. "It's a happy accident that it worked out as well as it did," he adds.

"Our results are a promising first step toward highly accurate solutions of much more sophisticated models," Chen says. Ultimately, an extension of such methods could lead to "reducing the overall cost of computational modeling of next-generation solar materials and devices."

Contact: Caroline McCall
Massachusetts Institute of Technology

Related biology news :

1. Evaluation of microscopy techniques may help scientists to better understand ancient plants
2. New stem cell technique promises abundance of key heart cells
3. New screening technique yields elusive compounds to block immune-regulating enzyme
4. Its a trap! New laboratory technique captures microRNA targets
5. New rearing system may aid sterile insect technique against mosquitoes
6. Scientists develop new technique that could improve heart attack prediction
7. Early detection techniques offer hope for improved outcomes in lung cancer patients
8. New genetic bar code technique establishes ability to derive DNA information from RNA
9. New synthetic biology technique boosts microbial production of diesel fuel
10. A new application allows online statistical analysis of gene-expression data
11. Computer simulations help explain why HIV cure remains elusive
Post Your Comments:
(Date:4/17/2017)... NXT-ID, Inc. (NASDAQ: NXTD ) ("NXT-ID" ... its 2016 Annual Report on Form 10-K on Thursday April 13, ... ... the Investor Relations section of the Company,s website at ... . 2016 Year Highlights: ...
(Date:4/13/2017)... According to a new market research report "Consumer IAM Market by ... Service, Authentication Type, Deployment Mode, Vertical, and Region - Global Forecast to ... USD 14.30 Billion in 2017 to USD 31.75 Billion by 2022, at ... ... MarketsandMarkets Logo ...
(Date:4/11/2017)... 11, 2017 Research and Markets has announced ... report to their offering. ... global eye tracking market to grow at a CAGR of 30.37% ... Tracking Market 2017-2021, has been prepared based on an in-depth market ... landscape and its growth prospects over the coming years. The report ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... CALIF. (PRWEB) , ... October 10, 2017 , ... San ... part of its corporate rebranding initiative announced today. The bold new look is ... reach, as the company moves into a significant growth period. , It will also ...
(Date:10/10/2017)... , ... October 10, 2017 , ... Dr. Bob Harman, ... his local San Diego Rotary Club. The event entitled “Stem Cells ... and had 300+ attendees. Dr. Harman, DVM, MPVM was joined by two human ...
(Date:10/10/2017)... (PRWEB) , ... October 10, 2017 , ... ... innovation and business process optimization firm for the life sciences and healthcare industries, ... conference in San Francisco. , The presentation, “Automating GxP Validation for Agile ...
(Date:10/9/2017)... ... October 09, 2017 , ... The award-winning American Farmer ... first quarter 2018. American Farmer airs Tuesdays at 8:30aET on RFD-TV. , With ... with the challenge of how to continue to feed a growing nation. At the ...
Breaking Biology Technology: