Title: High-accuracy electron correlation methods in new regimes: Coupled-cluster molecular dynamics Speaker: Andrew Taube, John von Neumann Fellow, Department 1435 Date/Time: Thursday, February 18, 2010, 1:30 – 2:30 pm (MST) Location: CSRI Building/Room 90 (Sandia NM), Building 915/Room S107 (Sandia CA) Brief Abstract: Combustion processes are sensitive to the detailed energetics of their potential energy surface. Therefore, predictive simulations of these processes require an accurate treatment of electronic correlation, which is most effectively included using coupled-cluster (CC) methods. Development of ab initio molecular dynamics driven by CC requires dealing with the high computational cost of these methods. One class of lower cost simplifications of CC are the linearized CC approaches (LinCC). However, these methods have been thought to be unsuitable for properties away from equilibrium because of pathological singularities along the potential energy surface. Recently, I have shown that these singularities can be removed in a computationally efficient way by introducing a simple regularization parameter. In particular, the proper choice of parameter will be shown to lead to results from the LinCCSD approximation that match or improve upon the more costly, and less parallelizable, nonlinear CCSD method. To perform MD simulations using LinCCSD requires an efficient parallel implementation. Robust scaling results for LinCCSD within the parallel ACESIII program will be shown and the implementation of the MD code will be described. Challenges to extending this approach beyond small systems and for higher accuracy will be discussed.CSRI POC: John Aidun, 844-1209 |