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BSSE Basis Set Superposition Error

BSSE Basis Set Superposition Error . Outline . Historical background What is BSSE? Why it happens? How we can correct it?. History. First time by Kestner for Helium dimer. By Jansen & Ros in 1969 for the protonation of carbon monoxide.

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BSSE Basis Set Superposition Error

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  1. BSSEBasis Set Superposition Error

  2. Outline • Historical background • What is BSSE? • Why it happens? • How we can correct it?

  3. History • First time by Kestner for Helium dimer. • By Jansen & Ros in 1969 for the protonation of carbon monoxide. • The term BSSE was introduced by Liu and Mclean in 1973.

  4. What is BSSE? Subsystem Subsystem B A Super system A B See larger basis set rather than isolated subsystems Absolute value of interaction energy goes up.

  5. Why it happens? When 2 chemicals like A & B want to become AB Then description of A in complex can be improved by functions of B and vice versa. But this extension is not possible in calculation of isolated A or B . A-B A + B 2s 2p 2s 2p

  6. A+B AB 2s and 2p 3s and 3p 5s and 5p 5s and 5p 5s and 5p but geometry of 2s and 2p 5s and 5p but geometry of 3s and 3p

  7. BSSE is important in: • Systems with weak interactions like van der Walls interactions • System with intramolecular interactions

  8. How we can correct it? 1-Counterpoise corrected gradient optimization 2-Function counterpoise method by Boys and Bernardi 3-Successive reaction counterpoise calculation 4-Symmetry Adapted Perturbation Theory

  9. Counterpoise correction The uncorrected interaction energy is The counterpoise interaction energy is The basis set for the subsystems contain the basis function of the whole molecule

  10. F= fragment frozen in AB geometry * = presence of ghost orbital For 2 fragments or atoms

  11. Example of counterpoise

  12. Boys and Bernardi function counterpoise Interaction energy : Basis set Boys and Bernardi energy: Geometry

  13. Example of Boys and Bernardi counterpoise Barrier height

  14. Cope rearrangement

  15. Successive reaction counterpoise [M(H2O)N-1 + H2O  M(H2O)N] M(L)N-1 + L → M(L)N

  16. Another example of SRC: Energy of H with basis function of F added and geometry of H

  17. Symmetry adapted perturbation theory antisymmetrizerer unperturbed wave functions V is the interaction operator, Classical electrostatic interaction energy Non classical exchange repulsion energy

  18. classical (Coulombic) electrostatic energy, Exchange antisymmetrization Second order exchange induction Induction energy Dispersion energy Exchange dispersion energy Hartree –Fock

  19. Symmetry adapted perturbation theory second order

  20. Example of SAPT: Hydrogen bonding HArF…N2 and HArF ….P2

  21. L: Linear B: Bent

  22. References: • Chemical Physics Letters 241(1995)140-145 • J Comput Chem 29:861-870,2008 • Chem. Rev. 1994 94,1837-1885 • International Journal of Quantum Chemistry ,19 January 2009 ,A. Clark • Journal of Molecular Structure (Therochem)342 (1995) 153-159 • Chemical Lists Letters 459 (2008) 44-48 • J Comput Chem 27: 1203-1210,2006 • Journal of Molecular Structure (Theochem) 537 (2001) 245-251 • J .Chem.Phys.98 (6) March 1993

  23. Thank you .

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