Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Capturing Those In-Between Moments: NIST Solves Timing Problem in Molecular Modeling

Colorized simulation of what happens to 1100 carbon atoms in a ‘flat’ sheet of graphene about 20 microseconds after the central atom is moved slightly upwards. Darker violet colors indicate atoms that have dropped below their original position, whereas the lighter green colors show where atoms have risen.

Credit: V.K. Tewary/NIST
Colorized simulation of what happens to 1100 carbon atoms in a ‘flat’ sheet of graphene about 20 microseconds after the central atom is moved slightly upwards. Darker violet colors indicate atoms that have dropped below their original position, whereas the lighter green colors show where atoms have risen. Credit: V.K. Tewary/NIST

Abstract:
A theoretical physicist at the National Institute of Standards and Technology (NIST) has developed a method for calculating the motions and forces of thousands of atoms simultaneously over a wider range of time scales than previously possible. The method overcomes a longstanding timing gap in modeling nanometer-scale materials and many other physical, chemical and biological systems at atomic and molecular levels.

Capturing Those In-Between Moments: NIST Solves Timing Problem in Molecular Modeling

Boulder, CO | Posted on November 16th, 2009

The new mathematical technique* can significantly improve modeling of atomic-scale processes that unfold over time, such as vibrations in a crystal. Conventional molecular dynamics (MD) techniques can accurately model processes that occur in increments measured in picoseconds to femtoseconds (trillionths to quadrillionths of a second). Other techniques can be used over longer periods to model bulk materials but not at the molecular level. The new NIST technique can access these longer time scales—in the critical range from nanoseconds to microseconds (billionths to millionths of a second)—at the molecular level. Scientists can now measure and understand what happens at key points in time that were not previously accessible, and throughout the full spectrum of time scales of interest in MD, says developer Vinod Tewary.

Modeling of material properties and physical processes is a valuable aid and supplement to theoretical and experimental studies, in part because experiments are very difficult at the nanoscale. MD calculations are usually based on the physics of individual atoms or molecules. This traditional approach is limited not only by time scale, but also by system size. It cannot be extended to processes involving thousands of atoms or more because today's computers—even supercomputers—cannot handle the billions of time steps required, Tewary says. By contrast, his new method incorporates a "Green's function," a mathematical approach that can calculate the condition of a very large system over flexible time scales in a single step. Thus, it overcomes the system size problem as well as the timing gap.

Tewary illustrated the new technique on two problems. He showed how a pulse propagating through a string of atoms, initiated by moving the middle atom, could be modeled for just a few femtoseconds with conventional MD, whereas the NIST method works for several microseconds. Tewary also calculated how ripples propagate in 1,100 carbon atoms in a sheet of graphene over periods up to about 45 microseconds, a problem that could not be solved previously. Normally thought of as a static flat sheet, the atoms in graphene actually must undulate somehow to remain stable, and the new technique shows how these ripples propagate. (See accompanying image and movie **). Consisting entirely of carbon atoms, graphene is a recently discovered honeycomb crystal material that may be an outstanding conductor for wires and other components in nanoscale electronics.

The new NIST technique is expected to enable modeling of many other processes that occur at time scales of nano- to microseconds, such as formation and growth of defects, conduction of heat, diffusion and radiation damage in materials. The technique could improve results in many different fields, from modeling of new nanotechnologies in the design stage to simulating the radiation damage from a "dirty bomb" over time.

NIST researchers plan to write a software program encoding the new technique to make it available to other users.

* V.K. Tewary. Extending time scale in molecular dynamics simulations: propagation of ripples in graphene. Physical Review B, Vol. 80, No. 16.. Published online Oct. 22, 2009.

Click http://www.nist.gov/public_affairs/techbeat/prb_gpn_wav_3d.avi to see a video clip (6.5 MB AVI file) that shows how ripples propagate in a sheet of graphene after the central atom is moved slightly upwards. The clip is a slow-motion version of action that occurs over about 45 microseconds.


####

About NIST
Founded in 1901, NIST is a non-regulatory federal agency within the U.S. Department of Commerce. NIST's mission is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.

For more information, please click here

Contacts:
Laura Ost

(301) 497-4880

Copyright © NIST

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Physics

A drop of water as a model for the interplay of adhesion and stiction June 30th, 2016

Particle zoo in a quantum computer: First experimental quantum simulation of particle physics phenomena June 23rd, 2016

News and information

A drop of water as a model for the interplay of adhesion and stiction June 30th, 2016

No need in supercomputers: Russian scientists suggest a PC to solve complex problems tens of times faster than with massive supercomputers June 30th, 2016

Surprising qualities of insulator ring surfaces: Surface phenomena in ring-shaped topological insulators are just as controllable as those in spheres made of the same material June 30th, 2016

How cancer cells spread and squeeze through tiny blood vessels (video) June 30th, 2016

Chemistry

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Quantum calculations broaden the understanding of crystal catalysts: Quantum mechanics and a supercomputer help scientists to identify the position of atoms on the surface of rutile June 22nd, 2016

Droplets finally all the same size -- in a nanodroplet library June 20th, 2016

Possible Futures

A drop of water as a model for the interplay of adhesion and stiction June 30th, 2016

No need in supercomputers: Russian scientists suggest a PC to solve complex problems tens of times faster than with massive supercomputers June 30th, 2016

Surprising qualities of insulator ring surfaces: Surface phenomena in ring-shaped topological insulators are just as controllable as those in spheres made of the same material June 30th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

Nanoelectronics

Soft decoupling of organic molecules on metal June 23rd, 2016

Tailored DNA shifts electrons into the 'fast lane': DNA nanowire improved by altering sequences June 22nd, 2016

Scientists engineer tunable DNA for electronics applications June 21st, 2016

Novel energy inside a microcircuit chip: VTT developed an efficient nanomaterial-based integrated energy June 10th, 2016

Materials/Metamaterials

Superheroes are real: Ultrasensitive nonlinear metamaterials for data transfer June 25th, 2016

Coexistence of superconductivity and charge density waves observed June 23rd, 2016

GraphExeter illuminates bright new future for flexible lighting devices June 23rd, 2016

Soft decoupling of organic molecules on metal June 23rd, 2016

Announcements

A drop of water as a model for the interplay of adhesion and stiction June 30th, 2016

No need in supercomputers: Russian scientists suggest a PC to solve complex problems tens of times faster than with massive supercomputers June 30th, 2016

Surprising qualities of insulator ring surfaces: Surface phenomena in ring-shaped topological insulators are just as controllable as those in spheres made of the same material June 30th, 2016

How cancer cells spread and squeeze through tiny blood vessels (video) June 30th, 2016

Tools

How cancer cells spread and squeeze through tiny blood vessels (video) June 30th, 2016

Oxford Instruments and Dresden High Magnetic Field Laboratory collaborate to develop HTS magnet technology components for high field superconducting magnet systems June 29th, 2016

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

FEI Launches Helios G4 DualBeam Series for Materials Science: The Helios G4 DualBeam Series features new capabilities to enable scientists and engineers to answer the most demanding and challenging scientific questions June 27th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic