LSU Researchers Use High-Performance Computing to Get Clearer Picture of How Atmospheric Particles Affecting Climate Change are Created
Scientists and researchers are using computational science technology to get a deeper understanding of nucleation, the beginning phase of many chemical and physical processes such as condensation, crystallization and precipitation, when nuclei of new particles form from molecular precursors.
This knowledge is essential in many areas, from controlling the properties of nanoparticles (i.e., size, shape, composition, morphology, etc.) to the reliable prediction of the formation of atmospheric aerosols that play an important role in climate change (i.e., particles in the atmosphere can affect how much light clouds are able to reflect and absorb, which affects the amount of sunlight transmitted to Earth).
Until now it has been a challenge for scientists to accurately model the climatic effects of aerosol particles because such predictions would require very precise data that clearly show how these particles form in the atmosphere. The challenge in this research is that the initial particles are so small and grow so quickly that direct observation is impossible, and scientists lack clear information to determine the size and composition of the initial clusters. The Intergovernmental Panel on Climate Change recently reported that aerosol particles and their effects on clouds are the biggest uncertainties in climate change models. This issue is very important to today’s scientists, who are addressing rapidly growing concerns about global warming.
At LSU, chemistry Professor Bin Chen’s research group is using simulations on high-performance computers to better understand this phenomenon and other industrial, biological, and environmental processes involving nucleation. Until recently, such simulations of nucleation have been extremely difficult, and most previous work has only offered a basic understanding of nucleation, rather than to give insight into the nucleation processes that can help scientists address specific, real-world problems.
Professor Chen’s research group has developed an advanced nucleation simulation methodology, which, along with LSU’s supercomputing resources and the advanced networking capabilities of the Louisiana Optical Network Initiative, or LONI, allowed Chen and graduate student Ricky Nellas, to perform the first atomistic molecular simulations of a multi-component nucleation process. Furthermore, they were able to incorporate complex molecules into the simulation, which allows the more accurate modeling of what occurs during atmospheric and industrial nucleation processes.
These simulations provide more insight than previously available into how particles form in the atmosphere, which can help scientists better understand the role they play in climate change. This understanding had been difficult to obtain with earlier, more simplified models. These simulations reproduced experimental results and provided a reasonable structural motif to explain the surprisingly large amount of organic content in some atmospheric aerosols. This structural motif has other important implications, from affecting the ability of clouds to absorb and reflect light to the improved transport and chemical reactivity of organic compounds in an atmospheric environment.
This work has led to two cover articles in the Physical Chemistry Chemical Physics journal, an invited feature article in the Journal of Physical Chemistry (to appear onto the cover of a June 2009 issue), and an invited chapter on Nucleation Mechanisms for Multicomponent Systems in Annual Reports of RSC (Royal Society of Chemistry).
Professor Chen’s group has further extended its approach to consider other systems and nucleation processes. Ricky Nellas has extended his work from nucleation in the Earth’s atmosphere to studying atmospheric nucleation processes on Mars.
Graduate students Sam Keasler and Hyunmi Kim and undergraduate student Joey Tauzin are performing simulations to better understand ion-induced nucleation, which are also part of atmospheric new particle formation. The group, in collaboration with Dr. Kalliat Valsaraj in the LSU Chemical Engineering Department and Dr. Collin Wick in the Department of Chemistry at Louisiana Tech University, is also investigating the attachment of pollutants to the surface of aerosol particles and how this might affect their chemical reactivity. In addition, they are expanding their research to problems of biological interest. Work is ongoing to develop methods to help understand the impact of solvent molecules on the structure of biological systems, in processes such as protein folding.
Publish Date:
05-05-2009
