Title: High-accuracy simulations of hydrocarbon combustion Speaker: Andrew Taube, University of Florida Date/Time: February 18, 2008 at 9:00 - 10:00am (MST) 8:00 - 9:00am (PST) Location: CSRI Bldg/Room 90 Sandia NM and videoconferenced to 915/S101 Sandia/CA Brief Abstract: My recent work focuses on improving the description of chemical bond breaking within coupled-cluster (CC) theory (the most powerful black box method for computational electronic structure of molecules). Near stationary points, CC methods attain chemical accuracy: errors of less than 1 kcal/mol. Away from these points, conventional CC methods deviate significantly. By using a more stable correction for the inclusion of triple excitations -- Lambda CCSD(T) -- with orbital optimization and improved numerical solvers, quantitative accuracy for bond breaking is achievable for a wider class of molecules than any previous CC method. This accuracy allows for confident predictions about unimolecular decomposition of high-energy materials, such as nitromethane and RDX. To describe dynamic chemical behavior of complicated molecules, new methods are needed that are fast enough to be run on-the-fly and accurate enough to provide quantitative insight. I propose a computationally practical technique to combine CC electronic structure with classical molecular dynamics and simulate hydrocarbon combustion. Combustion is sufficiently intricate, with open-shell species and multiple possible pathways, that sensitive effects of electron correlation are important. I will use linearized coupled-cluster with single and double excitations (LinCCSD) to describe the electrons. Because LinCCSD is stationary, linear, and size-extensive, it is an ideal platform to drive molecular dynamics for small gas-phase molecules, or for an active region within a larger cluster. For rapid, massively parallel and nonsingular calculations at the LinCCSD level, improved and regularized numerical procedures are necessary. Bio: Andrew Taube is a Ph.D. student with Rodney J. Bartlett in the Quantum Theory Project at the University of Florida. He graduated from Duke University with B.S. degrees in Chemistry and Mathematics (2003). Awards include a Barry M. Goldwater Scholarship (2002), a National Defense Science and Engineering Graduate Fellowship (2003) and a University of Florida Alumni Fellowship (2007).CSRI POC: Scott Collis, (1416) 284-1123 and Rick Muller, (1435) 284-2518 |