Theoretical Chemistry

Prof. Dr. Robert J. Buenker


Bergische Universitaet - Gesamthochschule Wuppertal
Fachbereich C - Theoretische Chemie
Gaussstr. 20
D-42097 Wuppertal
Germany
Phone: +49-202-439-2509 (Fax: +49-202-439-2581)
e-mail: buenker@uni-wuppertal.de

Research Interests and Points of Emphasis of Robert J. Buenker:

1. Ab Initio Calculations of Electronic Spectra of Small Molecules and Atoms: Transition Energies and Probabilities between Rovibrational Levels. 2. Development of the Multireference Single- and Double-Excitation CI Method for the Calculation of Electronic Wavefunctions and Properties: Author of MRD-CI Computer Program System widely employed in Germany, Canada, Greece, United Kingdom, Italy, Japan and the United States. 3. Study of Nonadiabatic Effects in the Electronic Spectra of Polyatomic Molecules Using Ab Initio MRD-CI Wavefunctions: Bound-Bound and Bound-Continuum Interactions and the Renner-Teller and Pseudo-Jahn-Teller Effects. 4. Treatment of Relativistic Effects Employing Two-Component Methods of Both Perturbational (Breit-Pauli) and Variational Type: Spin-orbit and Spin-spin Coupling Plus Use of Einstein Kinetic Energy Operator and the Darwin and Orbit-Orbit Interactions. Use of Averaged and Spin-orbit Relativistic Effective Core Potentials at the MRD-CI Level of Treatment. 5. Calculation of Atom-Atom and Atom-Molecule Scattering Cross Sections Based on Ab Initio CI Potential Energy Surfaces, Nonadiabatic and Spin-orbit Matrix Elements. 6. Application of Complex Scaling Techniques for the Description of Radiationless Processes such as Predissociation and Autoionization. 7. Theory and Calculations for the Radiative Decay of Positronium and Its Production of High-Energy Photons. 8. Use of Relativistic Effective Core Potentials in Ab Initio CI Treatments of Chemisorption and Cluster Reactions. 9. Theory of Photon Interactions with Transparent Media and Their Effect on the Speed of Light (Comparison with Gravitational Bending) 10. Study of the Effect of Inhomogeneous Magnetic Fields (Electroweak Stern-Gerlach Effect) in Neutron Decay and Its Relation to Parity Nonconservation Theory 11. Ab Initio SCF and CI Calculations for the Interactions of Positrons with Small Molecules

Recent Publications

(last update June 2007)

398 T. Kusakabe, R.J. Buenker and M. Kimura, Charge Transfer Processes in Collisions of H+ Ions with H2, D2, CO, CO2, CH4, C2H2, C2H6 and C3H8 Molecules Below 10 keV, Atomic and Plasma-Material Interaction Data for Fusion (IAEA), Vol. 10, pp. 151-161 (2002). 399 D.B. Kokh, A.B. Alekseyev and R.J. Buenker, Ab initio study of spectroscopic and ratiative characteristics of ion-pair states of the Cl2 molecule, J. Chem. Phys. 115, 9298-9310 (2001). 400 R. Suzuki, A. Watanabe, H. Sato, J.P. Gu, G. Hirsch, R.J. Buenker, M. Kimura and P.C. Stancil, Charge Transfer Processes in Collisions of Si4+ Ions with He Atoms at Intermediate Energies, Phys. Scripta T92, 345-347 (2001). 401 V. Rai, H.-P. Liebermann, R.J. Buenker, A.B. Alekseyev and R. Zellner, Electronic states and transitions of the TeX (X = Cl, Br, I) radicals, Mol. Phys. 100, 809-820 (2001). 402 K.K. Das, I.D. Petsalakis, H.-P. Liebermann, A.B. Alekseyev and R.J. Buenker, Ab initio spin-orbit CI calculations of the potential curves and radiative lifetimes of low-lying states of lead monofluoride, J. Chem. Phys. 116, 608-616 (2002). 403 M.A. Green, P.J.O. Teubner, L. Campbell, M.J. Brunger, M. Hoshino, T. Ishikawa, M. Kitajima, H. Tanaka, Y. Itikawa, M. Kimura and R.J. Buenker, Absolute Differential Cross Sections for Electron Impact Excitation of the 10.8 ? 11.5 eV Energy-Loss States of CO2, J. Phys. B: At. Mol. Opt. Phys. 35, 567-587 (2002). 404 I.D. Petsalakis, G. Theodorakopoulos and R.J. Buenker, Complex coordinate calculations on predissociation states of diatomic molecules, Russ. J. Phys. Chem. 76, Supplement 1, 1-6 (2002). 405 R.J. Buenker, Dynamical Aspects of Longitudinal Polarization Measurements for Weak Decay Processes: Suggestion for an Experimental Test of the Two-Component Theory of the Neutrino, Russ. J. Phys. Chem. 76, Supplement 1, 144-156 (2002). 406 N.S. Mosyagin, A.V. Titov, R.J. Buenker, H.-P. Liebermann and A.B. Alekseyev, GRECP/MRD-CI calculations on the Hg atom and the HgH molecule, Int. J. Quantum Chem. 88, 681-686 (2002). 407 T.A. Isaev, N.S. Mosyagin, A.V. Titov, A.B. Alekseyev and R.J. Buenker, GRECP/5e-MRD-CI calculation of the electronic structure of PbH, Int. J. Quantum Chem. 88, 687-690 (2002). 408 R.J. Buenker, Use of Hamilton?s canonical equations to modify Newton?s corpuscular theory of light: A missed opportunity, Khim. Fyz. 22 (10), 124-128 (2003). 409 R.J. Buenker and P.L. Mui¤o, Quantum Mechanical Relations for the Energy, Momentum and Velocity of Single Photons in Dispersive Media, Khim. Fyz. 23 (2), 111-116 (2004). 410 P.L. Mui¤o, A.M. Thompson and R.J. Buenker, Use of time-correlated single photon counting detection to measure the speed of light in water, Khim. Fyz. 23 (2), 117-128 (2004). 411 R.J. Buenker, J.L. Whitten, E.I. Izgorodina, H.-P. Liebermann and D.B. Kokh, Use of exchange maximization to generate starting vectors for self-consistent field calculations on metal cluster/adsorbate systems, J. Comput. Chem. 23, 943-949 (2002). 412 D.B. Kokh, A.B. Alekseyev, Yan Li, R.J. Buenker, The lowest 1(3PJ) and 2(3P2) ion-pair states of ClF: nonadiabatic effects and emission spectra, J. Chem. Phys. 117, 628-635 (2002). 413 G. V. Golubkov, M. G. Golubkov and R.J. Buenker, Dissociative recombination of slow electrons with molecular oxygen ions in the intense laser field, Khim. Fyz. 23 (2), 53-60 (2004). 414 A.Z. Devdariani and R.J. Buenker, He (21,3S) Quasimolecule at Low Temperatures, Khim. Fyz. 23 (2), 61-64 (2004). 415 I.D. Petsalakis, G. Theodorakopoulos, H.-P. Liebermann and R.J. Buenker, Potential energy curves and dipole transition moments for excited electronic states of XeKr and ArNe, J. Chem. Phys. 117, 3639-3646 (2002) 416 G. Theodorakopoulos, I.D. Petsalakis, H.-P. Liebermann, R.J. Buenker and J. Koput, Ab initio calculations on electronic states of CaOH, J. Chem. Phys. 117, 4810-4819 (2002). 417 D. Giri, R.J. Buenker and K.K. Das, Electronic Spectrum of Tin Oxide: MRDCI Study, J. Phys. Chem. A. 106, 8790-8797 (2002). 418 K.D. Setzer, J. Borkowska-Burnecka, W. Zyrnicki, A.M. Pravilov, E.H. Fink, K.K. Das, H.-P. Liebermann, A.B. Alekseyev and R.J. Buenker, Experimental and Theoretical Study of the Electronic States and Spectra of PbLi, J. Mol. Spectrosc. 217, 127-141 (2003). 419 P.G. Alcheev, R.J. Buenker, V.E. Chernov and B.A. Zon, Oscillator strengths for Rydberg states in ArH calculated in QDT approximation, J. Mol. Spectrosc. 218, 190-196 (2003). 420 L. Pichl, Y. Li, H.-P. Liebermann, R.J. Buenker and M. Kimura, Charge transfer for the ground state O+ (4S) ion in collision with H2 molecules, J. Chem. Phys. 118, 4872-4877 (2003). 421 R.J. Buenker, The Lorentz Transformation Sign Ambiguity and Its Relation to Measured Faster-than-c Photon Speeds, Khim. Fyz. 23 ( 7), 80-82 (2004). 422 A.B. Alekseyev, H.-P. Liebermann and R.J. Buenker, Spin-orbit Multireference Configuration Interation Method and Applications to Systems Containing Heavy Atoms, in: Relativistic Molecular Calculations, edited by K. Hirao and M. Ishikawa (World Scientific, Singapore, 2003), pp. 65-105. 423 S.N. Rai, H.-P. Liebermann, R.J. Buenker and M. Kimura, Ab initio CI calculations of the potential curves and nonadiabatic coupling matrix elements for collisions of protons with the ethylene molecule, Int. J. Quantum Chem. 95, 866-876 (2003). 424 R.J. Buenker, H.-P. Liebermann, D. B. Kokh, E.I. Izgorodina and J.L. Whitten, Configuration Interaction Study of the Excited States of CO Adsorbed on a Pt97 Cluster, Chem. Phys. 291, 115-124 (2003). 425 T.W. Imai, M. Kimura, J.P. Gu, G. Hirsch, R.J. Buenker, J.G. Wang, P.C. Stancil and L. Pichl, Ab initio study of one- and two-electron transfer processes in collisions of Ne2+ with He at low to intermediate energies, Phys. Rev. A. 68, 012716, 1-7 (2003). 426 G.V. Golubkov, M.G. Golubkov, A.N. Romanov and R.J. Buenker, Dissociative Recombination e- + O2+ ? O(1D) + O(3P) in a strong laser field, Phys. Chem. Chem. Phys. 5, 3174-3182 (2003). 427 L. Pichl, Y. Li, R.J. Buenker and M. Kimura, Electron capture and excitation in collisions of O+ (4S, 2D, 2P) with H2 molecules, Phys. Rev. A 69, 062715, 1-10 (2004). 428 I.D. Petsalakis, G. Theodorakopoulos and R.J. Buenker, Theoretical ab initio study of the electronic states of KrH and KrH+. Quantum defect and complex coordinate calculations on the Rydberg states of KrH, J. Chem. Phys. 119, 2004-2013 (2003). 429 M. Tachikawa, R.J. Buenker and M. Kimura, Bound states of positron with urea and acetone molecules using configuration interaction ab initio molecular orbital approach, J. Chem. Phys. 119, 5005-5009 (2003). 430 A.J. Yencha, P. Baltzer, A.J. Cormack, Y. Li, H.-P. Liebermann, A.B. Alekseyev and R.J. Buenker, High-resolution photoelectron spectroscopy of HI and DI: Experimental and theoretical analysis of the A 2?+ ion system, J. Chem. Phys. 119, 5943-5948 (2003). 431 T. Kusakabe, M. Kimura, L. Pichl, R.J. Buenker and H. Tawara, Observation of significant differences in charge transfer between collisions of H+ ions with H2 and with D2 molecules in the high-eV to low-KeV range, Phys. Rev. A 68, 050701(R), 1-4 (2003). 432 L. Pichl, R.J. Buenker and M. Kimura, Calculation of Cross Sections for Proton and Antiproton Stopping in Molecules, Adv. Quant. Chem. 46, 165-193 (2004). 433 R.M. Lingott, H.-P. Liebermann, A.B. Alekseyev and R.J. Buenker, Ab initio study of the BiSe and BiTe electronic spectra: What happens with X2-X1 emission in the heavier Bi chalcogenides?, J. Chem. Phys. 120, 7476-7482 (2004). 434 S. Wu, Y. Chen, X. Yang, Y. Guo, Y. Li, R.J. Buenker and P. Jensen, Vibronic transition moments and line intensities for H2O+, J. Mol. Spectrosc. 225, 96-106 (2004). 435 Y. Li, H.-P. Liebermann, R.J. Buenker and L. Pichl, A coupled treatment of 1?+ and 3? states of AgH molecule, Chem. Phys. Letters 389, 101-107 (2004). 436 D.B. Kokh, A.B. Alekseyev and R.J. Buenker, Theoretical study of the UV absorption in Cl2: Potentials, transition moments, extinction coefficients, and Cl*/Cl branching ratio, J. Chem. Phys. 120, 11549-11556 (2004). 437 R.J. Buenker, Comparison of the phenomena of light refraction and gravitational bending, Khim. Fys. 24 (4), 29-35 (2005). 438 R.J. Buenker, The Lorentz Transformation for photons in dispersive media, Khim. Fys. 24 (9), 19-24 (2005). 439 L. Pichl, M. Kimura, Y. Li and R.J. Buenker, Branching ratios for secondary processes of water ions induced by proton beams in radiation therapy of cancer, IEEE Trans. Nucl. Sci. 51, 1407-1411 (2004). 440 H. Suno, S.N. Rai, H.-P. Liebermann, R.J. Buenker, M. Kimura and R.K. Janev, Elastic and inelastic processes in H+ + CH2 collisions between 0.5 and 1.5 keV, Phys. Rev. A 70, 032703, 1-7 (2004). 441 L. B. Zhao, P.C. Stancil, J.P. Gu, H.-P. Liebermann, Y. Li, P. Funke, R.J. Buenker, B. Zygelman, M. Kimura and A. Dalgarno, Radiative charge transfer in collisions of O with He+, Ap. J. 615, 1063-1072 (2004). 442 M. Tachikawa, R.J. Buenker and M. Kimura, Geometry relaxation effects for molecules as a result of binding with a positron, J. Chem. Phys. 121, 9191-9192 (2004). 443 T. Kusakabe, L. Pichl, R. J. Buenker, M. Kimura and H. Tawara, Isotope effect in charge transfer collisions of slow H+ and D+ ions with H2, HD, and D2 molecules, Phys. Rev. A 70, 052710, 1-7 (2004). 444 D. Dai, M.-H. Whangbo, A. Ugrinov, S.C. Sevov, F. Wang, L. Li, A. Villesuzanne, A. B. Alekseyev, H.-P. Liebermann and R.J. Buenker, Analysis of the effect of spin-orbit coupling on the electronic structure of the Bi22- anion in (K-crypt)2Bi2 on the basis of relativistic electronic structure calculations, J. Phys. Chem. A. 109, 1675-1683 (2005). 445 R. Suzuki, S. N. Rai, H.-P. Liebermann, R. J. Buenker, L. Pichl and M. Kimura, Elastic and electron-capture processes in H+ + C2H4 collisions below the 10-keV regime, Phys. Rev. A 71, 032710, 1-10 (2005). 446 A.B.Alekseyev, D.B. Kokh and R.J. Buenker, HI photofragmentation revisited. Comment on ?Probing excited electronic states using vibrationally mediated photolysis: Application to hydrogen iodide,? J. Phys. Chem. A 109, 3094-3096 (2005). 447 R.J. Buenker, H.-P. Liebermann, V. Melnikov, M. Tachikawa, L. Pichl and M. Kimura, Positron binding energies for alkali hydrides, J.Phys.Chem. A 109, 5956-5964 (2005). 448 L. B. Zhao, P.C. Stancil, H.-P. Liebermann, P. Funke and R.J. Buenker, Charge transfer between O+ ions and helium, Phys. Rev. A 71, 060701 (R), 1-4 (2005). 449 C. Y. Lin, P.C. Stancil, J.P. Gu, R.J. Buenker and M. Kimura, Electron capture in collisions of N+ with H and H+ with N, Phys. Rev. A 71, 062708, 1-7 (2005). 450 L. Pichl, M. Tachikawa, R.J. Buenker, M. Kimura and J.-M. Rost, The effects of positron binding and annihilation mechanisms in biomolecules on PET resolution, IEEE Trans. Nucl. Sci. 52, 2810-2817 (2005). 451 L. B. Zhao, P.C. Stancil, J.P. Gu, H.-P. Liebermann, P. Funke, R.J. Buenker and M. Kimura, Electron capture in collisions of S with H+, Phys. Rev. A 71, 062713, 1-11 (2005). 452 L. Pichl, Y. Li, R. J. Buenker, M. Kimura, J. Horacek and I. Schneider, Electronic potential energy of H2- and CHe4+ diatomic ions, J. Plasma Fusion Research SERIES 7, 249-252 (2006). 453 V. Rai-Constapel, H.-P. Liebermann, R. J. Buenker and S. N. Rai, Ab initio MRD-CI study of the spectrum of the TeO molecule employing relativistic effective core potentials, J. Phys. Chem. A 110, 404-411 (2006). 454 D.B. Kokh, R. J. Buenker, H.-P. Liebermann, L. Pichl and J.L. Whitten, Theoretical study of the CH2 + O photodissociation of formaldehyde adsorbed on the Ag (111) surface, J. Phys. Chem. B 109, 18070-18080 (2005). 455 L. B. Zhao, P. C. Stancil, J.-P. Gu, G. Hirsch, R. J. Buenker, T. W. Imai and M. Kimura, Charge transfer between S2+ and He: A comparative study of quantal and semiclassical approaches, Phys. Rev. A 72, 032719, 1-9 (2005). 456 R. Suzuki, S. N. Rai, H.-P. Liebermann, R. J. Buenker, L. Pichl and M. Kimura, Elastic and inelastic processes in H+ + C2H6 collisions below the 10-keV regime, Phys. Rev. A 72, 052710, 1-10 (2005). 457 C. M. Dutta, J.-P. Gu, G. Hirsch, R. J. Buenker, P. Nordlander and M. Kimura, Charge-transfer processes in F2+ + H ? F+ + H+ collisions and the reverse process at low keV energies, Phys. Rev. A 72, 052715, 1-7 (2005). 458 L. Pichl, R. Suzuki, M. Kimura, Y. Li, R. J. Buenker, M. Hoshino and Y. Yamazaki, Angular dependence of double electron capture in collisions of C4+ with He. Stueckelberg oscillations in the differential cross-section for capture into C2+ (1s22s2 1S), Eur. Phys. J. D 38, 59-64 (2006). 459 R.J. Buenker, H.-P. Liebermann, M. Tachikawa, L. Pichl and M. Kimura, Multireference CI study of the potential curves and properties of positronic complexes of alkali hydrides, Nucl. Instr. and Meth. in Phys. Res. B 247 , 47-51(2006). 460 F. A. Gianturco, J. Franz, R. J. Buenker, H.-P. Liebermann, L. Pichl, J.-M. Rost, M. Tachikawa and M. Kimura, Positron binding to alkali hydrides: the role of molecular vibrations, Phys. Rev. A 73, 022705, 1-9 (2006). 461 M. Kimura, L. Pichl, Y. Li, H.-P. Liebermann, R. J. Buenker and I. F. Schneider, Steric effect in O+/H2 and H+/H2O collisions. Charge transfer in H2O+ and H3O+ collision intermediate systems, Eur. Phys. J. D 38, 85-91 (2006). 462 H. Suno, S. N. Rai, H.-P. Liebermann, R. J. Buenker, M. Kimura and L. Pichl, Elastic ˙and inelastic processes in H+ + NH2 collisions between 0.5 and 1.5 keV, Phys. Rev. A 74, 012701, 1-7 (2006). 463 A. Devdariani, E. Chesnokov, A. Zagrebin, M. G. Lednev, I. D. Petsalakis, G. Theodorakopoulos, H.-P. Liebermann and R. J. Buenker, Quasi-molecular radiative transitions produced by thermal and low-temperature collisions: Ar (3p6 1S0-3p54s3P2) -He, Chem. Phys 330, 101-112 (2006). 464 D. B. Kokh, R. J. Buenker and J. L. Whitten, Trends in adsorption of open-shell atoms and small molecular fragments on the Ag (111) surface, Surf. Sci. 600, 5104-5113 (2006). 465 M. Honigmann, R. J. Buenker and H.-P. Liebermann, Complex SCF and MRD-CI calculations for the 2?g resonance state of N2-, J. Chem. Phys. 125, 234304, 1-12 (2006) 466 L. B. Zhao, J. G. Wang, P. C. Stancil, J.-P. Gu, H.-P. Liebermann, R. J. Buenker and M. Kimura, Radiative charge transfer in Ne2+ + He collisions, J. Phys. B: At. Mol. Opt. Phys. 39, 5151-5160 (2006). 467 M. Hoshino, L. Pichl, Y. Kanai, Y. Nakai, M. Kitajima, M. Kimura, Y. Li, H.-P. Liebermann, R. J. Buenker, H. Tanaka and Y. Yamazaki, Experimental and theoretical study of double-electron capture in collisions of slow C4+ (1s2 1S) with He (1s2 1S), Phys. Rev. A. 75, 012716, 1-6 (2007). 468 R. J. Buenker, H.-P. Liebermann and A. Z. Devdariani, Ab initio spin-orbit configuration interaction calculations for high-lying states of the HeNe quasi-molecule, J. Phys. Chem. A 111, 1307-1318 (2007). 469 S. Mada, K. Hida, M. Kimura, L. Pichl, H.-P. Liebermann, Y. Li and R. J. Buenker, Charge transfer and electronic excitation on collisions of protons with water molecules below 10 eV, Phys. Rev. A 75, 022706, 1-7 (2007). 470 R. J. Buenker, H-P. Liebermann, L. Pichl, M. Tachikawa and M. Kimura, Role of the electric dipole moment in positron binding to the ground and excited states of the BeO molecule, J. Chem. Phys. 126, 104305, 1-7 (2007). 471 G. J. Vazquez, J. M. Amero, H.-P. Liebermann, R. J. Buenker and H. Lefebvre-Brion, An insight into the lowest Rydberg states of CH, J. Chem. Phys. 126, 164302, 1-13 (2007). 472 T. Kusakabe, H. Tawara, M. Kimura, J.-P. Gu and R. J. Buenker, Charge-transfer cross sections of H+ ions in collisions with Ne atoms in the energy range below 4.0 keV, Phys. Rev. A 75, 044701, 1-3 (2007). 473 A. B. Alekseyev, H.-P. Liebermann and R. J. Buenker, An ab initio study of the CH3I photodissociation. I. Potential energy surfaces, accepted for publication in J. Chem. Phys.. 474 A. B. Alekseyev, H.-P. Liebermann and R. J. Buenker, An ab initio study of the CH3I photodissociation. II. Transition moments, absorption spectra, I* quantum yields, accepted for publication in J. Chem. Phys. 475 C. Y. Lin, P. C. Stancil, Y. Li, J.-P. Gu, H.-P. Liebermann, R. J. Buenker and M. Kimura, Vibrationally-resolved charge transfer for proton collisions with CO and H collsions with CO+, accepted for publication in Phys. Rev. A. 476 D. B. Kokh, R. J. Buenker, H.-P. Liebermann, and J. L. Whitten, Theoretical study of the photo-induced C-H bond cleavage in formaldehyde adsorbed on the Ag(111) surface, accepted for publication in J. Phys. Chem. C. 477 C. Y. Lin, P. C. Stancil, H.-P. Liebermann, P. Funke and R. J. Buenker, Elastic and inelastic processes in collisions of Na(3s,3p) with He from thermal energies to the ultracold, submitted for publication. 478 T. Kusakabe, K. Gotanda, M. Kimura, S. N. Rai, H.-P. Liebermann, and R. J. Buenker, Vibrational temperature effect on charge-transfer processes in collisions of H+ and O+ ions with C2H4 molecules at energies below 10 keV/u, submitted for publication. 479 V. Rai-Constapel, H.-P. Liebermann, R. J. Buenker, M. Honigmann and P. Jensen, A theoretical study of TeOH in its electronic ground state, submitted for publication. 480 A. B. Alekseyev, H.-P. Liebermann, and R. J. Buenker, Theoretical study of the ArH+ photodissociation, submitted for publication.

Members of the Group

  • Dr. Aleksey Alekseyev alexeev@uni-wuppertal.de
  • Priv. Doz. Dr. Ihsan Boustani boustani@uni-wuppertal.de
  • Dr. Daria Kokh kokh@uni-wuppertal.de
  • Dr. Vidisha Rai-Constapel (rai@uni-wuppertal.de)
  • Cand.-Chem. Rainer Lingott
  • Dipl.-Phys.-Ing. H.-Peter Liebermann (system administrator)
  • Peter Funke (system administrator)
  • Marion Litz (secretary)
    Last modified 25/5/2007 by Daria Kokh