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Jeremy Lai Texas Academy of Mathematics and Science

The correlation-consistent composite approach: Implementation of the resolution-of-the-identity approximation. Jeremy Lai Texas Academy of Mathematics and Science Dr . Angela K. Wilson, Department of Chemistry College of Arts and Sciences University of North Texas.

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Jeremy Lai Texas Academy of Mathematics and Science

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  1. The correlation-consistent composite approach: Implementation of the resolution-of-the-identity approximation Jeremy Lai Texas Academy of Mathematics and Science Dr. Angela K. Wilson, Department of Chemistry College of Arts and Sciences University of North Texas

  2. Computational Chemistry • Industries: • Materials Science • Petrochemicals • Medicine • Computers can work overnight! • Especially useful for • Dangerous reactions • Short-lived reactions • Expensive reactions

  3. Ab initio Methods • Extremely accurate • No experimental evidence • Computational cost • CPU Time • Disk Space Requirements • Memory Requirements

  4. Why so expensive? • Schrodinger Equation: • Can’t solve that, we make approximations • Hartree-Fock Theory • Møller-Plesset perturbation theory • Coupled-Cluster theory • For two electron interaction:

  5. Coulomb Integral • H2 has 2 electrons • C2H6O has 20 electrons • C6H12 has 36 electrons

  6. Cyclohexane C6H12

  7. Protein

  8. Protein Dimer

  9. The correlation-consistent composite approach (ccCA) • 3.3 years or 20 days? • ccCA made medium-sized molecules more practical • 4 additive steps • Reference Energy (MP2) • Correlation Energy (CCSD(T)) • Core-Valence Energy (MP2) • Scalar-Relativistic Energy (MP2)

  10. Resolution-of-the-Identity Approximation • Unity operator • Theoretically reduces computational cost by 2 orders of magnitude

  11. Experiment • Tested RI-ccCA with G2/97 Test Set • Over 100 second-row and third-row molecules • Used Molpro, a computation chemistry software package • Used the Department of Chemistry’s CRUNTChsupercomputers

  12. Does it work? 1 2 3 5 4

  13. Does it work? (cont.) 1 2 3 5 4

  14. Summary of RI-ccCA • Favorable relationship with molecular size • Reduces CPU time • Reduces Disk Space • Reduces Wall Time • Makes large-sized molecules more practical • Carbon nanotubes • Small proteins • Next-generation fuels

  15. Summary of RI-ccCA (cont.) • More efficient for small-sized molecules and medium-sized • This means we can now use $1000 Computer instead of $100,000 Supercomputer

  16. Acknowledgements • Dr. Angela K. Wilson • Principal Investigator • Dr. Brian P. Prascher • Graduate Student • Center for the Advancement of Scientific Computing and Modeling (CASCaM) • University of North Texas • TAMS Summer Research Scholarship

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