Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Supercomputers Reveal Strange, Stress-Induced Transformations in World's Thinnest Materials


Interested in an ultra-fast, unbreakable, and flexible smart phone that recharges in a matter of seconds? Monolayer materials may make it possible. These atom-thin sheets—including the famed super material graphene—feature exceptional and untapped mechanical and electronic properties. But to fully exploit these atomically tailored wonder materials, scientists must pry free the secrets of how and why they bend and break under stress.

Fortunately, researchers have now pinpointed the breaking mechanism of several monolayer materials hundreds of times stronger than steel with exotic properties that could revolutionize everything from armor to electronics. A Columbia University team used supercomputers at the U.S. Department of Energy’s Brookhaven National Laboratory to simulate and probe quantum mechanical processes that would be extremely difficult to explore experimentally.

Brookhaven National Laboratory

IBM supercomputer Blue Gene/Q, the latest addition to the New York Center for Computational Sciences.

They discovered that straining the materials induced a novel phase transition—a restructuring in their near-perfect crystalline structures that leads to instability and failure. Surprisingly, the phenomenon persisted across several different materials with disparate electronic properties, suggesting that monolayers may have intrinsic instabilities to be either overcome or exploited. The results were published in the journal Physical Review B.

“Our calculations exposed these monolayer materials’ fundamental shifts in structure and character when stressed,” said study coauthor and Columbia University Ph.D. candidate Eric Isaacs. “To see the beautiful patterns exhibited by these materials at their breaking points for the first time was enormously exciting—and important for future applications.”

The team virtually examined this exotic phase transition in graphene, boron nitride, molybdenum disulfide, and graphane—all promising monolayer materials.

Simulated Shattering

Monolayer materials experience strain on atomic scales, demanding different investigative expertise than that of the average demolition crew. Isaacs and his collaborators turned to a mathematical framework called density functional theory (DFT) to describe the quantum mechanical processes unfolding in the materials.

“DFT lets us study materials directly from fundamental laws of physics, the results of which can be directly compared to experimental data,” said Chris Marianetti, a professor of materials science at Columbia University and coauthor of the study. “We supply the fundamental constants and the material’s nuclei, and using DFT we can closely approximate real characteristics of the material under different conditions.”

In this study, DFT calculations revealed the materials’ atomic structures, stress values, vibrational properties, and whether they acted as metals, semiconductors, or insulators under strain. Toggling between or sustaining those conductive properties are particularly important for future applications in microelectronics.

“Testing all the different atomic configurations for each material under strain boils down to a tremendous amount of computation,” Isaacs said. “Without the highly parallel supercomputing resources and expertise at Brookhaven, it would have been nearly impossible to pinpoint this transition in strained monolayers.”

Twisted Atomic Half-Pipe

Everything breaks under enough stress, of course, but not everything meaningfully transforms along the way. A bending oak branch, for example, doesn’t enter a strange transition phase as it creeps toward its breaking point—it simply snaps. Monolayer materials, it turns out, play by very different rules.

Within the honeycomb-like lattices of monolayers like graphene, boron nitride, and graphane, the atoms rapidly vibrate in place. Different vibrational states, which dictate many of the mechanical properties of the material, are called “modes.” As the perfect hexagonal structures of such monolayers are strained, they enter a subtle “soft mode”—the vibrating atoms slip free of their original configurations and distort towards new structures as the materials break.

“Imagine a skateboarder in a half-pipe,” Isaacs said. “Normally, the skater glides back and forth but remains centered over the bottom. But if we twist and deform that half-pipe enough, the skateboarder rolls out and never returns—that’s like this soft mode where the vibrating atoms move away from their positions in the lattice.”

Softly Breaking

The researchers found that this vibrational soft mode caused lingering, unstable distortions in most of the known monolayer materials. In the case of graphene, boron nitride, and graphane, the backbone of the perfect crystalline lattice distorted toward isolated hexagonal rings. The soft mode distortion ended up breaking graphene, boron nitride, and molybdenum disulfide.

As the monolayers were strained, the energetic cost of changing the bond lengths became significantly weaker—in other words, under enough stress, the emergent soft mode encourages the atoms to rearrange themselves into unstable configurations. This in turn dictates how one might control that strain and tune monolayer performance.

“Our work demonstrates that the soft mode failure mechanism is not unique to graphene and suggests it might be an intrinsic feature of monolayer materials,” Isaacs said.

Monolayer Renovations

Armed with this knowledge, researchers may now be able to figure out how to delay the onset of the newly characterized instabilities and improve the strength of existing monolayers. Beyond that, scientists may even be able to engineer new ultra-strong materials that anticipate and overcome the soft mode weakness.

“Beyond the thrill of the discovery, this work is immediately useful to a large community of researchers excited to learn about and exploit graphene and its cousins,” Isaacs said. “For example, we’ve been working with Columbia experimentalists who use a technique called ‘nanoindentation’ to experimentally measure some of what we simulated.”

The work was supported by the National Science Foundation (Grant No. CMMI-0927891) and the New York Center for Computational Sciences, a joint venture between Brookhaven Lab and Stony Brook University that is supported by the U.S. Department of Energy and the State of New York.

Brookhaven Lab is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

Justin Eure | newswise
Further information:

Further reports about: DFT Energy Supercomputers fundamental graphene monolayer strain structures transition vibrational

More articles from Materials Sciences:

nachricht Dielectric film has refractive index close to air
12.10.2015 | North Carolina State University

nachricht New Artificial Cells Mimic Nature’s Tiny Reactors
09.10.2015 | Department of Energy, Office of Science

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Light Touch May Help Animals and Robots Move on Sand and Snow

Having a light touch can make a hefty difference in how well animals and robots move across challenging granular surfaces such as snow, sand and leaf litter. Research reported October 9 in the journal Bioinspiration & Biomimetics shows how the design of appendages – whether legs or wheels – affects the ability of both robots and animals to cross weak and flowing surfaces.

Using an air fluidized bed trackway filled with poppy seeds or glass spheres, researchers at the Georgia Institute of Technology systematically varied the...

Im Focus: Reliable in-line inspections of high-strength automotive body parts within seconds

Nondestructive material testing (NDT) is a fast and effective way to analyze the quality of a product during the manufacturing process. Because defective materials can lead to malfunctioning finished products, NDT is an essential quality assurance measure, especially in the manufacture of safety-critical components such as automotive B-pillars. NDT examines the quality without damaging the component or modifying the surface of the material. At this year's Blechexpo trade fair in Stuttgart, Fraunhofer IZFP will have an exhibit that demonstrates the nondestructive testing of high-strength automotive body parts using 3MA. The measurement results are available in a matter of seconds.

To minimize vehicle weight and fuel consumption while providing the highest level of crash safety, automotive bodies are reinforced with elements made from...

Im Focus: Kick-off for a new era of precision astronomy

The MICADO camera, a first light instrument for the European Extremely Large Telescope (E-ELT), has entered a new phase in the project: by agreeing to a Memorandum of Understanding, the partners in Germany, France, the Netherlands, Austria, and Italy, have all confirmed their participation. Following this milestone, the project's transition into its preliminary design phase was approved at a kick-off meeting held in Vienna. Two weeks earlier, on September 18, the consortium and the European Southern Observatory (ESO), which is building the telescope, have signed the corresponding collaboration agreement.

As the first dedicated camera for the E-ELT, MICADO will equip the giant telescope with a capability for diffraction-limited imaging at near-infrared...

Im Focus: Locusts at the wheel: University of Graz investigates collision detector inspired by insect eyes

Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.

Inspired by insects

Im Focus: Physicists shrink particle accelerator

Prototype demonstrates feasibility of building terahertz accelerators

An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...

All Focus news of the innovation-report >>>



Event News

EHFG 2015: Securing healthcare and sustainably strengthening healthcare systems

01.10.2015 | Event News

Conference in Brussels: Tracking and Tracing the Smallest Marine Life Forms

30.09.2015 | Event News

World Alzheimer`s Day – Professor Willnow: Clearer Insights into the Development of the Disease

17.09.2015 | Event News

Latest News

Siemens to build light rail vehicles for cities in the US

12.10.2015 | Press release

Siemens to add an additional 173 megawatts to Clyde onshore wind farm in Scotland

12.10.2015 | Press release

Scientists paint quantum electronics with beams of light

12.10.2015 | Physics and Astronomy

More VideoLinks >>>