Summary of Research Interests of N. Yngve Öhrn

Development of novel, rigorous, computationally tractable theory of molecular energetics and dynamics.

• Explicitly time-dependent theory beyond the adiabatic approximation for the study of molecular processes and atomic collisions.
• Application of such theory to the study of elementary chemical reactions, such as electron transfer (intra - and intermolecular), energy transfer, and rearrangements.
• Application to first principles calculations of rate constants for elementary gas phase reactions.

• Application to the interaction of molecular systems with external fields, such as intense laser fields.
• Application to the study of optical and conduction properties of polymeric systems
• Development and application of Green's function or propagator methods to the theoretical study of molecular spectroscopy.

Representative publications

1. J. Linderberg and Y. Öhrn, Propagators in Quantum Chemistry ,Academic Press, London 1973.
2. G. D. Purvis and Y. Öhrn, "Atomic and Molecular Electronic Properties and Spectra from the Electron Propagator", J. Chem. Phys.60 , 4063 (1974).
3. G. D. Purvis and Y. Öhrn, "The Transition State , the Electron Propagator and the Equation of Motion Method", J. Chem. Phys. 65 , 917 (1976).
4. G. D. Purvis and Y. Öhrn, "Accurate Molecular Ionization Potentials from the Electron Propagator", Int. J. Quantum Chem. S11, 359 (1977).
5. G. Born, H. Kurtz, and Y. Öhrn, "Elementary Finite Order Perturbation Theory for Vertical Ionization Energies", J. Chem. Phys. 68 , 74 (1978).
6. Y. Öhrn and J. Linderberg, "The Consistent RPA Ground State", Int. J. Quantum Chem. 15, 343 (1979)
7. Y. Öhrn and G. Born, "Molecular Electron Propagator Theory and Calculations", in Advances of Quantum Chemistry, Vol. 13, 1981.
8. J. V. Ortiz and Y. Öhrn, " Electron Propagator Calculations of Molecular Electron Affinities", Chem. Phys. Letters 77, 548 (1981).
9. J. V. Ortiz, B. Weiner, and Y. Öhrn, "The AGP Wavefunction and Its Relation to Other Descriptions of Electronic Structure", Int. J. Quantum Chem. S15, 113 (1982).
10. Y. Öhrn and J. Linderberg, "Hyperspherical Coordinates in Four Particle Systems", Mol. Phys. 49, 53 (1983).
11. B. Weiner and Y. Öhrn, "Correlated Electronic States of the LiH Molecule Studied with the Polarization Propagator", J. Phys. Chem. 91, 563 (1987).
12. E. Deumens, B. Weiner, and Y. Öhrn, "Time-Dependent Variational Principle on the Group SO(2r); Generalizations of Time-Dependent Hartree-Fock", Nucl. Phys. A466, 85 (1987).
13. E. Sangfelt, R. Roychowdhury, B. Weiner, and Y. Öhrn, "Generalized Tamm-Dancoff (GTDA) and Generalized Random Phase Approximation (GRPA) Calculations on LiH, Be and the Lithium Molecule", J. Chem. Phys. 86, 4523 (1987).
14. E. Deumens and Y. Öhrn, "Electron-Nuclear Dynamics with Diabatic and Adiabatic Wave Packets", J. Phys. Chem. 92, 3181 (1988).
15. Y. Öhrn, "Propagator Methods for Molecular Electronic Spectra" in Aspects of Many-Body Effects in Molecules and Extended Systems, Calcutta 1988; Lecture Notes in Chemistry Vol 50 Spriger Verlag, New York, 1989, Ed. D. Mukherjee.
16. J. Linderberg, Y. Öhrn, B. Vessal, and S. Padkjaer, " Numerical Implementation of Reactive Scattering Theory", J. Chem. Phys.90 , 6254 (1989).
17. B. Weiner, E. Deumens, and Y. Öhrn, "Coherent State Formulation of Multi-Configurational States", J. Math. Phys. 32, 1166 (1991).
18. Y. Öhrn, E. Deumens, A. Diz, R. Longo, J. Oreiro, and H. Taylor, "Time-Evolution of Electrons and Nuclei in Molecular Systems", in NATO ASI SeriesB:Physics, Vol. 299, p 279, Plenum Press, Eds. J. Broeckhove and L. Lathouwers.
19. E. Deumens, A. Diz, H. Taylor, and Y. Öhrn, " Time-Dependent Dynamics of Electrons and Nuclei", J. Chem. Phys. 96, 6820 (1992).
20. B. Weiner, E. Deumens, and Y. Öhrn, "Coherent State Approach to Electron Nuclear Dynamics with an Antisymmetrized Geminal Power State", J. Math. Phys. 35. 1139 (1994).
21. E. Deumens, A. Diz, R. Longo, and Y. Öhrn, "Time-Dependent Theoretical Treatments of the Dynamics of Electrons and Nuclei in Molecular Systems", Rev. Modern. Phys. 66, 917 (1994).
22. J.-L. Calais, E. Deumens, and Y. Öhrn, "A Model for Electron-Nuclear Dynamics of a Monatomic Chain", J. Chem. Phys.101, 3989 (1994).
23. B. Champagne and Y. Öhrn, " Ab Initio Longitudinal Polarizabilities of Conjugated Stereoregular Polymers with a Carbon Backbone", Chem Phys. Letters 217, 551 (1994).
24. R. Longo, B. Champagne, and Y. Öhrn, "Electron Propagator Theory and Application", Theor. Chimica Acta 90, 397 (1995).
25. J. Morales, A. Diz, E. Deumens, and Y. Öhrn, "Molecular Vibrational State Distributions in Collisions", Chem. Phys. Letters233, 392 (1995).
26. A. Diz, Y. Öhrn, and J. R. Sabin, "Dynamic Charge States and Energy Deposition of Swift Helium Ions in Neon", Nucl. Instr. Meth. B96, 633 (1995).
27. J. Morales, A. Diz, E. Deumens, and Y. Öhrn, " Electron Nuclear Dynamics of Proton Collisions with Hydrogen Molecules at 30 eV", J. Chem. Phys.103, 9968 (1995).
28. Y. Öhrn, J. Oreiro, and E. Deumens, "Bond Making and Bond Breaking in Molecular Dynamics", Int. J. Quantum Chem.58, 583 (1996).
29. B. Champagne, J.-M. Andre, and Y. Öhrn, "Ab Initio Dynamic Polarizabilities of Polymers. I. Hydrogen Chain Models", Int. J. Quantum Chem.57 , 811 (1996).
30. E. Deumens and Y. Öhrn, "Wavefunction phase space; An approach to the dynamics of molecular systems", J. Chem.Soc.,Faraday Trans., 93, 919 (1997).
31. B. Champagne, E. Deumens, and Y. Öhrn, "Vibrations and soliton dynamics of positively charged polyacetylene chains"J. Chem. Phys. 107, 5433 (1997)
32. D. Jacquemin, J. A. Morales, E. Deumens, and Y. Öhrn, "Electron nuclear dynamics of proton collisions with methane at 30 eV"J. Chem. Phys. 107,6146 (1997)
33. J. Broeckhove, M. D. Coutinho-Neto, E. Deumens, and Y. Öhrn, "The electron nuclear dynamics of LiH and HF in an intense laser field", Phys. Rev. A56, 4996 (1997)
34. M. Hedström, J. A. Morales, E. Deumens, and Y. Öhrn, "Electron nuclear dynamics of H⁺ + H₂O collisions", Chem. Phys. Lett.279, 241 (1997)
35. M. Hedström, E. Deumens, and Y. Öhrn, " Electron nuclear dynamics of charge transfer collisions of protons with atomic oxygen", Phys. Rev. A57, 2625 (1998)
36. R. Cabrera-Trujillo, J. R. Sabin, Y. Öhrn, and J. Oddershede, Phys. Rev. A57, 3115 (1998)
37. J. A. Morales, E. Deumens, and Y. Öhrn, "On rotational coherent states in molecular quantum dynamics"J. Math. Phys.40, 766 (1999)
38. R. Cabrera-Trujillo, J. R. Sabin, Y. Öhrn, and E. Deumens,"Direct differential cross section calculations for ion-atom and atom-atom collisions in the keV range."Phys. Rev. A.61, 032719 (2000)
39. R. Cabrera-Trujillo, J. R. Sabin, Y. Öhrn, and E. Deumens,"Charge Exchange and Threshold Effects in the Energy Loss of Slow Projectiles" Phys. Rev. Lett.84, 5300 (2000)
40. Remigio Cabrera-Trujillo, E.rik Deumens, Yngve Öhrn, and John R. Sabin, "Impact parameter dependence of electronic and nuclear energy loss of swift ions: H⁺ -> He, and H⁺ -> H", Nucl. Instr. Meth. B168, 484-492 (2000)

R. Cabrera-Trujillo,  J. R. Sabin, Y.  Öhrn , and E. Deumens, "Charge Exchange and Threshold Effects in the Energy Loss of Slow Projectiles" Phys. Rev. Lett. 84, 5300 (2000).
41. R. Cabrera-Trujillo, Y. Öhrn, E. Deumens, and J. R. Sabin, "Stopping cross section in the low- to intermediate energy range: Study of protons on atomic N, O, and F",  Phys. Rev. A  62, 052714(1-9) (2000)
42. R. Cabrera-Trujillo, J. R. Sabin, E. Deumens, and Y. Öhrn, "Stopping cross section and charge exchange study on the He⁺->Ne system, Application of reactors in research and industry: Sixteenth International Conference AIP Conference Proceedings, 562, 3 (2000).
43. Y.  Öhrn,  Elements of Molecular Symmetry, Wiley&Sons, New York (2000)
44. E. Deumens and Y.  Öhrn, "Complete Electron Nuclear Dynamics" , J. Phys. Chem. A105, 2660 (2001).
45. A. Blass, E. Deumens, and Y.  Öhrn, "Rovibrational Analysis of Molecular Collisions using Coherent States", J. Chem. Phys. 115, 8633 (2001).
46. R. Cabrera-Trujillo, Y. Öhrn, J. R. Sabin, and E. Deumens, "Molecular target and projectile angular scattering effects in stopping power and charge exchange at low to intermediate energies" Phys. Rev. A 65,024901 (2002).
47. R. Cabrera-Trujillo, Y. Öhrn, E. Deumens, and J. R. Sabin, "Trajectory and molecular bidning effects in stopping cross sections for hydrogen beams on H₂  " J. Chem. Phys. 116, 2783 (2002).
48. M. Coutinho-Neto, E. Deumens, and Y. Öhrn, "Abstraction and Exchange Mechanisms for the D₂ +NH₃ ⁺ Reaction at Hyperthermal Collision Energies  ", J. Chem. Phys.116, 2794 (2002)
49. Y. Öhrn and E. Deumens,  "Electron Nuclear Dynamics", in Effects of Electronic Degenerate States on Nuclear Dynamical Processes,  Adv. Chem. Phys.  Vol. 124, 323-353 (Eds. M. Baer and G. D. Billing) Wiley&Son, New York 2002.
50. Y. Öhrn, "Density, Density Matrix, or Propagator", Adv. Quantum. Chem. Vol. 41,  35 (Eds. J. R. Sabin and E. Brandas) , Academic Press, New York 2002.
51. S. A. Malinovskaya, R. Cabrera-Trujillo, J. R. Sabin, E. Deumens, and Y.  Öhrn, "Dynamics of collisions of protons with acetylene molecules at 30 eV", J. Chem. Phys. 117, 1103 (2002).
52. R.  Cabrera -Trujillo, J. R.  Sabin, E.  Deumens, and Y.  Öhrn, "Stopping cross sections for N⁴⁺    ->  H at low projectile velocity" Phys. Rev. A 66, 022706(1-7) (2002). 
53. D.  Jacquemin, B.  Champagne, J.-M.  Andre, E.  Deumens, and Y.   Öhrn,  "Integral algorithm and density matrix integration scheme for ab initio band structure calculations on polymeric systems" , J. Comp. Chem. 23, 1430-1444 (2002).
54. R. Cabrera-Trujillo, Y.  Öhrn, E. Deumens, J. R. Sabin, and B. G. Lindsay, "Theoretical and experimental studies of the  H ⁺  + N ₂  system: Differential cross sections for direct and charge transfer scattering at keV energies",  Phys. Rev. A 66, 042712 (2002).
55. R. Cabrera-Trujillo, J. R. Sabin, Y. Öhrn,  and  E. Deumens, "Energy loss studies  of protons colliding with etahne: Preliminary results", J. Elec. Spectr. 129, 303-308 (2003).
56. R. Cabrera-Trujillo, J. R. Sabin, and Y. Öhrn, "Dynamical Processes in Stopping Cross Sections", Adv. Quantum Chem. 45, 99-124 (2004).
57. R. Cabrera-Trujillo, J. R. Sabin, E. Deumens, and Y. Öhrn,  "Calculation of Cross Sections in Electron Nuclear Dynamics", Adv. Quantum Chem. 47, 251-272 (2004)
58. R. Cabrera-Trujillo, Y. Öhrn,  E. Deumens, and J. R. Sabin, "Application of END Theory to the H + D ₂ -> HD + D  reaction" J. Phys. Chem. A 108, 8935-8940 (2004).
59. J. Linderberg and Y. Öhrn, Propagators in Quantum Chemistry , expanded 2'nd edition, Wiley&Sons, New York, 2004.
60. R. Cabrera-Trujillo, Y. Öhrn, E. Deumens, J. R. Sabin, and B. G. Lindsay, "Absolute differential and total cross sections for direct and charge-transfer scattering of keV protons by O₂ " , Phys. Rev. A 70, 042705 (2004).
61. B. Killian, R. Cabrera-Trujillo, E. Deumens, and Y. Öhrn, "Resonant charge transfer between H⁺ and H from 1 to 5000 eV", J. Phys. B: At, Mol, Opt. Phys. 37, 1-15 (2004).
62. R. Cabrera-Trujillo, J. R. Sabin, Y. Öhrn, and E. Deumens, "Stopping of swift antiprotons by hydrogen atoms and the Barkas correction." Phys. Rev. A 71, 012901 (2005).
63. D. Masiello, E. Deumens, and Y. Öhrn, "Dynamics of an atomic electron and its electromagnetic field in a cavity"  Phys. Rev. A 71, 032108 (2005).
64. R. Cabrera-Trujillo, J. R. Sabin, E. Deumens, and Y. Öhrn, "Orientational effects of energy deposition by protons in water"  Adv. Quantum Chem. 48, 47-57 (2005).
65. D. Masiello, E. Deumens, and Y. Öhrn, On the canonical formulation of electrodynamics and wave mechanics", Adv. Quantum Chem. 49, 249-297, (2005).
66. Y. Öhrn and E. Deumens, "Time-Dependent, Direct, Nonadiabatic Molecular Reaction Dyneamics", in Quantum Dynamics of Complex Molecular Systems, Springer Seriesin Chemical Physics Vl. 83, 2006, Eds. D. Micha and I. Burghart.
67. N. Stolterfoht, R. Hellhammer, Z. Pesic, R. Cabrera-Trujillo, E. Deumens, Y. Öhrn, and J. R. Sabin, "Charge exchange and fragmentation in slow collisions of He²⁺  with  water molecules" Adv. Quantum Chem. 52, 149-170 (2007).