Metadynamics technique offers insight into mineral growth and dissolution

Jan 23, 2012

By using a novel technique to better understand mineral growth and dissolution, researchers at the Department of Energy's Oak Ridge National Laboratory are improving predictions of mineral reactions and laying the groundwork for applications ranging from keeping oil pipes clear to sequestering radium.

The mineral barite was examined to understand mineral growth and dissolution generally, but also because it is the dominant scale-forming mineral that precipitates in and reservoirs in the North Sea. Oil companies use a variety of compounds to inhibit scale formation, but a better understanding of how barite grows could enable them to be designed more efficiently.

Additionally, barium can trap radium in its crystal structure, so it has the potential to contain the radioactive material.

In a paper featured on this month's cover of the , the ORNL-led team studied barite growth and dissolution using metadynamics, a critical technique that allows researchers to study much slower reactions than what is normally possible.

"When a mineral is growing or dissolving, you have a hard time sorting out which are the important reactions and how they occur because there are many things that could be happening on the surface," said Andrew Stack, ORNL geochemist and lead author on the paper. "We can't determine which of many possible reactions are controlling the rate of growth."

To overcome this hurdle, ORNL Chemical Sciences Division's Stack started with molecular dynamics, which can simulate energies and structures at the . To model a mineral surface accurately, the researchers need to simulate thousands of atoms. To directly measure a slow reaction with this many atoms during mineral growth or dissolution might take years of supercomputer time. Metadynamics, which builds on molecular dynamics, is a technique to "push" reactions forward so researchers can observe them and measure how fast they are proceeding in a relatively short amount of computer time.

With the help of metadynamics, the team determined that there are multiple intermediate reactions that take place when a barium ion attaches or detaches at the mineral surface, which contradicts the previous assumption that attachment and detachment occurred all in a single reaction.

"Without metadynamics, we would never have been able to see these intermediates nor determine which ones are limiting the overall reaction rate," Stack said.

To run computer simulations of mineral growth, researchers used the Large-scale Atomic/Molecular Massively Parallel Simulator, a code developed by Sandia National Laboratories. Co-authors on the paper are the Curtin University (Australia) Nanochemistry Research Institute's Paolo Raiteri and Julian Gale.

Explore further: Triplet threat from the sun

Related Stories

New insights into the origin of life on Earth

Dec 11, 2006

In an advance toward understanding the origin of life on Earth, scientists have shown that parts of the Krebs cycle can run in reverse, producing biomolecules that could jump-start life with only sunlight and a mineral present ...

X-ray Method Images Ions at Interface

Jun 12, 2004

A team led by Northwestern University researchers at the U.S. Department of Energy’s Argonne National Laboratory have taken the guesswork out of interfacial structure determination. The researchers are the first to show th ...

Recommended for you

Triplet threat from the sun

13 hours ago

The most obvious effects of too much sun exposure are cosmetic, like wrinkled and rough skin. Some damage, however, goes deeper—ultraviolet light can damage DNA and cause proteins in the body to break down ...

Towards controlled dislocations

Oct 20, 2014

Crystallographic defects or irregularities (known as dislocations) are often found within crystalline materials. Two main types of dislocation exist: edge and screw type. However, dislocations found in real ...

Chemists tackle battery overcharge problem

Oct 17, 2014

Research from the University of Kentucky Department of Chemistry will help batteries resist overcharging, improving the safety of electronics from cell phones to airplanes.

Surface properties command attention

Oct 17, 2014

Whether working on preventing corrosion for undersea oil fields and nuclear power plants, or for producing electricity from fuel cells or oxygen from electrolyzers for travel to Mars, associate professor ...

User comments : 0