After the thaw

February 19th, 2014
Permafrost creates a polygonal landscape, irregularity that makes simulating thawing’s impact on climate change a challenge requiring advanced algorithms and high-performance computers. (Photo: Konstanze Piel, Alfred Wegener Institute.)

Simulations of melting permafrost promise changes in climate modeling.


Rewinding the universe

December 17th, 2013
A cosmological simulation with the Nyx code. The white lines represent the edges of a small sample of the universe, about 50 million light years on a side, at redshift about 3.5 billion years after the Big Bang. Shown are baryons at two different densities: blue is about twice the mean baryon density in the universe; the yellow is about 10 times. The blue regions approximate areas that give rise to the Lyman-Alpha forest signal; yellow is a rough representation of regions where gas coalesces into galaxies. (Simulation by Zarija Lukić, Lawrence Berkeley National Laboratory. Image by Casey Stark, University of California, Berkeley.)

Dark energy propels the universe to expand faster and faster. Researchers are using simulations to test different conceptions about how this happens.


Balancing act

October 31st, 2013
Scalability (red line) of the triples part of the re-normalized EOMCCSD(T) approach in excited-state calculations for porphyrin-coronene complex. Timings were determined from calculations on the Jaguar Cray XT5 computer system.

A Pacific Northwest National Laboratory researcher is developing approaches to spread the work evenly over scads of processors in a high-performance computer and to keep calculations clicking even as part of the machine has a hiccup.