title: GPU-Based Implementations of the Noniterative Regularized-CCSD(T) Corrections: Applications to Strongly Correlated Systems.
abstract: The details of the graphical processing unit (GPU) implementation of the most computationally intensive (T)-part of the recently introduced regularized CCSD(T) (Reg-CCSD(T)) method [ Kowalski , K. ; Valiev , M. J. Chem. Phys. 2009 , 131 , 234107 ] for calculating electronic energies of strongly correlated systems are discussed. Parallel tests performed for several molecular systems show very good scalability of the triples part of the Reg-CCSD(T) approach. We also discuss the performance of the Reg-CCSD(T) GPU implementation as a function of the parameters defining the partitioning of the spinorbital domain (tiling structure). The accuracy of the Reg-CCSD(T) method is illustrated on three examples: the methyfluoride molecule, dissociation of dodecane, and open-shell Spiro cation (5,5'(4H,4H')-spirobi[cyclopenta[c]pyrrole] 2,2',6,6'-tetrahydro cation), which is a frequently used model to study electron transfer processes. It is demonstrated that a simple regularization of the cluster amplitudes used in the noniterative corrections accounting for the effect of triply excited configurations significantly improves the accuracies of ground-state energies in the presence of strong quasidegeneracy effects. For methylfluoride, we compare the Reg-CCSD(T) results with the CR-CC(2,3) and CCSDT energies, whereas for Spiro cation we compare Reg-CCSD(T) results with the energies obtained with completely renormalized CCSD(T) method. Performance tests for the Spiro, dodecane, and uracil molecules are also discussed.
authors.affiliation: Department of Computer Science and Engineering, The Ohio State University , Columbus, Ohio, United States.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Ma
authors.affiliation: Computational Sciences and Mathematics Division, Pacific Northwest National Laboratory , Richland, Washington, United States.
authors.forename: Sriram
authors.initials: S
authors.lastname: Krishnamoorthy
authors.affiliation: Computational Sciences and Mathematics Division, Pacific Northwest National Laboratory , Richland, Washington, United States.
authors.forename: Oreste
authors.initials: O
authors.lastname: Villa
authors.affiliation: William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States.
authors.forename: Karol
authors.initials: K
authors.lastname: Kowalski