University of Pennsylvania scientist
Michael Klein and his colleague Dongsup Kim have used PSC's
CRAY T3E and the prototype Terascale Computing System to
develop quantum-level knowledge of superacids. Essential
tools of the chemical industry, superacids have a powerful
ability to break down raw petroleum, leading to such
products as high-strength plastics and lead-free high-octane
gasoline. Though industry uses hundreds of thousands of tons
of superacid annually, there has been little understanding
of how they work chemically.
Through simulations at PSC, Klein and Kim are
shedding new light on why some superacids are stronger than
others, showing that they form clusters with a ring-like
structure, a previously unrecognized key to their chemistry.
Their simulations also explained experiments showing that
superacids conduct electricity better than can be accounted
for by ionic diffusion, the normal process by which
electrons in solution roam from ion to ion.
This graphic from Klein's computational
study illustrates the details of a mechanism called "proton
jumping" that underlies the electrical conductivity of
superacids. In the strongest superacid, antimony
pentafluoride, an excess proton (yellow) attaches to a
fluorine atom (red), and they stay together as they "jump"
along a linked chain of hydrogen-fluoride molecules (blue
and green). The simulation shows that the proton and its
fluorine partner travel across three bonds in 81.5
billion-millionths of a second (10-15 sec.).