Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chemist Tames Longstanding Electron Computation Problem

12.12.2008
For 50 years theoretical chemists have puzzled over the problem of predicting many-electron chemistry with only two electrons, which many thought intractable and perhaps impossible to solve. David Mazziotti has devised a new approach to the problem.

When the University of Chicago’s David Mazziotti talks about chemistry, perhaps he is thinking about how the behavior of all of the electrons in a molecule can be anticipated from the behavior of just two of its electrons.

For 50 years theoretical chemists have puzzled over the problem of predicting many-electron chemistry with only two electrons, which many thought intractable and perhaps impossible to solve. Mazziotti, an associate professor in chemistry, will present a new approach to tuning his solution to the problem for exceptional computational accuracy and efficiency in the Dec. 12 issue of Physical Review Letters.

“We can do all these calculations using a desktop computer,” Mazziotti said.

“We’re getting accuracy and efficiency that supercedes some of the traditional techniques, so it really opens up a whole new ballgame.”

Scientists have grappled with the problem for decades because a detailed statistical description of electrons’ positions in a molecule can reveal whether a particular chemical reaction will occur. But the number of electrons in an atom or molecule can range from 10 to hundreds or thousands.

Even the most powerful computers lack the power to perform these calculations, which become increasingly expensive as more electrons are added to the mix. The computational cost stems from the laws of quantum mechanics, the branch of physics that governs the behavior of atoms and molecules. Mazziotti’s advance means that chemists will be able to compute the electronic properties of a given molecule with greater accuracy at a lower cost.

Mazziotti anticipates that his research tool will enable scientists to more rapidly solve a wide range of problems in chemistry, including the chemistry of free radicals. Free radicals are molecules with unpaired electrons that play a key role in reactions that deplete atmospheric ozone and create greenhouse gases. Radical-type reactions are also important in the design of new drugs and more efficient combustion engines.

Mazziotti began working on the problem of using two electrons to represent many electrons in the mid-1990s as a graduate student at Harvard University. His graduate school mentor, Nobel laureate Dudley Herschbach, has called the quest “a ‘holy grail’ of theoretical chemistry.”

Speaking of Mazziotti’s progress in 2006, Herschbach said that “David Mazziotti has made a major advance in fundamental theory.”

Herschbach employed a football analogy to illustrate Mazziotti’s method, known to theoretical chemists as the 2-electron Reduced Density Matrix (2-RDM) method.

In this analogy, a coach could automatically determine the actions of an entire team by simply plotting the motion of just two to three players: the quarterback and one running back/receiver, with auxiliary help from one lineman.

“His method requires dealing with just pairs and trios of electrons,” Herschbach said.

The late Joseph Mayer, a professor in chemistry at the University of Chicago from 1946 until 1960, was one of the first scientists to propose doing electronic structure calculations for many-electron atoms and molecules by using just two electrons.

In the 2-RDM approach, one determines the probabilities for finding a pair of electrons at different locations in an atom or molecule. But a problem arises, Mazziotti said. “If one wants to work with these two-electron distributions, one has to make sure that they actually represent the many-electron system adequately.”

Mazziotti has in fact developed several two-electron approaches that target different levels of accuracy and efficiency. The previous approaches tuned for maximum accuracy have applications to highly challenging problems like bi-radicals (molecules with two unpaired electrons), electron-rich materials, and molecular conductivity.

The latest tool extends independent work by Christian Kollmar at the Zernike Institute for Advanced Materials in the Netherlands as well as work with University of Chicago graduate student Eugene DePrince. It is tuned for high efficiency and impressive accuracy for applicability to a very wide range of chemical problems.

“We view 2-RDM theory as a platform that we can now tune, essentially, to get high accuracy or high efficiency or some combination of both of those for different molecular systems,” Mazziotti said.

Last year Mazziotti published a book, Two-Electron Density Matrix Mechanics for Many-Electron Atoms and Molecules, which serves as a roadmap for scientists in his field. More than 20 scientists contributed chapters to the volume, which summarizes historical and recent advances in the field.

Supporting Mazziotti’s work are the National Science Foundation, the American Chemical Society Petroleum Research Fund, Microsoft Corporation, the Dreyfus Foundation and the David and Lucile Packard Foundation.

Steve Koppes | Newswise Science News
Further information:
http://www.uchicago.edu

More articles from Physics and Astronomy:

nachricht Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)

nachricht Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>