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Towards PPCC

Towards PPCC. So Hirata Quantum Theory Project University of Florida. Sanibel Symposium 2008, Parallel CC Workshop. Issues at petascale.

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Towards PPCC

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  1. Towards PPCC So Hirata Quantum Theory Project University of Florida Sanibel Symposium 2008, Parallel CC Workshop

  2. Issues at petascale • Increased complexity of algorithms and implementations – computerized derivation and implementation / optimization, portability, extensibility, maintainability / parallel middleware • Multilevel hierarchical parallelism – hierarchical structures of chemical computing / linear scaling, PES scan, ab initio MD/MC • Fault tolerance, restart capability, calculation log, and verification – parallel middleware / compartmentation of calculations / redundant calculations / hierarchical methods

  3. Mathematical expressions A parallel computer program Automated symbolic algebraHirata, JPCA (2003); Hirata, TCA (2006); Hirata, JP Conf. Ser. (2006) Definition of a many-electron theory

  4. Automated symbolic algebraHirata, JPCA (2003); Hirata, TCA (2006); Hirata, JP Conf. Ser. (2006) • Correct scaling by factorized,reusable intermediates • Spin, point-group, and permutationsymmetries • Dynamic load balancing parallelism; scalable • Runtime adjustment of memory usage Never send a human to do a machine’s job Agent Smith “The Matrix”

  5. Implemented methodsHirata JPCA (2003); Hirata TCA (2006); Hirata JP Conf Ser (2006) Electron Attachment Theory EA-EOM-CCSD EA-EOM-CCSDT EA-EOM-CCSDTQ Kamiya & Hirata (2007) Linear Expansion CIS, CISD, CISDT, CISDTQ Hirata JPCA (2003) CI CIS+perturbation CIS(D), CIS(3), CIS(4) Hirata JCP (2005) Ionization Theory IP-EOM-CCSD IP-EOM-CCSDT IP-EOM-CCSDTQ Kamiya & Hirata JCP (2006) Other CIS+2nd order D-CIS(2), SCS-CIS(D) SOS-CIS(D) Fan & Hirata (2007) Excited State Theories EOM-CCSD EOM-CCSDT EOM-CCSDTQ Hirata JCP (2004) Perturbation MP2, MP3, MP4 Hirata JPCA (2003) PT CC Combined CC+PT CCSD(T) CCSD(2)T, CCSD(3)T CCSD(2)TQ, CCSD(3)TQ CCSDT(2)Q, CR-CCSD(T) Hirata et al. JCP (2004) Shiozaki, Hirao & Hirata JCP (2007) Cluster Expansion CCD, CCSD, CCSDT, CCSDTQ, LCCD, LCCSD, QCISD Hirata JPCA (2003) EOM-CC+perturbation EOM-CCSD(2)T, EOM-CCSD(2)TQ EOM-CCSD(3)T Shiozaki, Hirao & Hirata JCP (2007)

  6. CC-R12, EOM-CC-R12, Λ-CC-R12Shiozaki, Kamiya, Hirata, & Valeev, in preparation (2008) New types of ansatz – new symbolic algabra code Significantly more complex equations Longer computational sequences Multiple hotspots Possibilities of various approximations Toru Shiozaki University of Florida

  7. CC-R12 R12-CCSD on 100 processors ~ CCSD on 100,000 processors

  8. Linear scaling CC Linear scaling CCSD on 1 processor ~ CCSD on 100,000 processors

  9. N-body (N > 2) Coulomb in dipole-dipole approximation 1 and 2-body Coulomb Exchange Correlation Fast methods for water clustersHirata et al. MP (2005) Pair energy in the presence of dipole field

  10. Fast methods: excited statesHirata et al. MP (2005) A record EOM-CCSD aug-cc-pVDZ calculation for a 247-atom system Constant scaling!

  11. Coupled-cluster for solids • Maddox (Nature, 1988): “One of the continuing scandals in the physical sciences is that it remains in general impossible to predict the structure of even the simplest crystalline solids from a knowledge of their chemical composition. … Solids such as crystalline water (ice) are still thought to lie beyond mortals’ ken.”

  12. 1 and 2 type solid formic acid

  13. Molecular crystals Hydrogen fluoride Formamide Ice XI

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