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Quadrupole interaction in the solid halogens – a new (not final) look H. Haas

Quadrupole interaction in the solid halogens – a new (not final) look H. Haas Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2685 Sacavém, Portugal, and CERN/EP-SC, CH-1211 Geneve-23, Switzerland, e-mail: heinz.haas@cern.ch. Experimentalists credo (old):

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Quadrupole interaction in the solid halogens – a new (not final) look H. Haas

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  1. Quadrupole interaction in the solid halogens – a new (not final) look H. Haas Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2685 Sacavém, Portugal, and CERN/EP-SC, CH-1211 Geneve-23, Switzerland, e-mail: heinz.haas@cern.ch Experimentalists credo (old): If theory and experiment do not agree, theory must be wrong

  2. Quadrupole interaction in the solid halogens – a new (not final) look H. Haas Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2685 Sacavém, Portugal, and CERN/EP-SC, CH-1211 Geneve-23, Switzerland, e-mail: heinz.haas@cern.ch Experimentalists credo (old): If theory and experiment do not agree, theory must be wrong Theorists credo (new): If theory and experiment do not agree, experiment must be wrong

  3. Quadrupole interaction in the solid halogens – a new (not final) look H. Haas Instituto Tecnológico e Nuclear, Estrada Nacional 10, P-2685 Sacavém, Portugal, and CERN/EP-SC, CH-1211 Geneve-23, Switzerland, e-mail: heinz.haas@cern.ch Experimentalists credo (old): If theory and experiment do not agree, theory must be wrong Theorists credo (new): If theory and experiment do not agree, experiment must be wrong I will try to convince you: If theory and experiment do agree, they may both be wrong !

  4. The structure of the solid halogens

  5. The experimental situation

  6. The experimental situation A mess !

  7. The advent of theory

  8. More new theories

  9. More new theories A mess !

  10. Structural parameters as function of temperature

  11. Structural data extrapolated to T = 0

  12. Experimental frequencies (MHz) extrapolated to T = 0

  13. Temperature dependence Cl2 (Nakamura 67)

  14. Halogen Q (with H. Petrilli)

  15. WIEN2k results (1021 V/m2)

  16. WIEN2k results (1021 V/m2) Conclusion: Present DFT overestimates the frequency shift due to the intermolecular interaction by a factor 2 to 2.5

  17. WIEN2k results (1021 V/m2) Conclusion: Present DFT overestimates the frequency shift due to the intermolecular interaction by a factor 2 to 2.5 Assumption: The calculated intermolecular interaction overestimates h by a similar factor

  18. Final results

  19. Comparison with experiments Conclusions:Experiment for Br2 must be grossly wrongThe low value of h (>.3) for Cl2 is favored

  20. Expanded lattice calculations

  21. Expanded lattice calculations Conclusion: With proper choice of the degree of expansion, fixed to the result at T=0, one can compute the EFG also for high T

  22. Temperature dependence Cl2 (Nakamura 67)

  23. Temperature dependence Cl2 (new)

  24. Temperature dependence Br2

  25. Temperature dependence I2

  26. General conclusions • We need a proper theory for treatment of the intermolecular interaction ! • For better calculations one would require more accurate crystal structure data • A remeasurement of h for solid Br2 is highly recommended • Interesting effects are predicted for the temperature dependence of the NQR frequency for Br2 and I2

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