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  • 101.
    Froelich, Piotr
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Saenz, Alejandro
    Calculation of the beta-decay spectrum of the T-2 molecule beyond the sudden impulse approximation1996Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 77, nr 23, s. 4724-4727Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The probability distribution of electronic excitations of HeT+ following the beta decay of the T-2 molecule has been calculated for the first time in the beyond sudden impulse approximation, removing the uncertainty related to the reliability of this appr

  • 102.
    Froelich, Piotr
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi. Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Weyrich, Wolf
    On the relativistic corrections to the cross-section for inelastic scattering of photons on atomic electrons1996Inngår i: ZEITSCHRIFT FUR PHYSIK D-ATOMS MOLECULES AND CLUSTERS, ISSN 0178-7683, Vol. 38, nr 3, s. 185-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The relativistic cross-section for inelastic photon scattering on bound electrons is reconsidered, and lowest-order corrections to the sudden-impulse approximation are derived. These corrections stem from including the presence of the external (Coulombic)

  • 103.
    Fängström, Torbjörn
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Edvardsson, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Ericsson, Marie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Lunell, Sten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Enkvist, Christer
    Density functional study of chlorine-oxygen compounds related to the ClO self-reaction1998Inngår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 66, nr 3, s. 203-217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Geometrical parameters, vibrational frequencies, relative stabilities, and dissociation energies of the three stable Cl2O2 isomers and the OClO and ClOO radicals were investigated by density functional theory (DFT). The present analysis shows that DFT using hybrid functionals is capable of describing these systems to at least the same degree of accuracy as ab initio methods. The average absolute bond-length deviation of ClClO2,, ClOOCl, and ClO2, from experimental results is 0.024/0.027 Angstrom, with a maximum deviation for the dichlorine peroxide O-O bond equal to 0.072/0.063 Angstrom, for the B3PW91 and B3LYP functionals, respectively. The average absolute bond-angle deviation for the hybrid functionals is 0.8 degrees. Harmonic vibrational frequencies calculated with DFT give for all Cl-O compounds good agreement with experiments. The dissociation energies of ClOOCl, OClO, and ClOO were found to be in good agreement with experiments, the average error being less than 1.2 kcal/mol. The two isomers chloryl chloride (ClClO2,) and dichlorine peroxide (ClOOCl) were found to be approximately 9 kcal/mol more stable than the chlorine chlorite (ClOClO) isomer. The ClOO isomer is predicted to be 3.0 kcal/mol more stable than OClO, in accordance with the experimental value of 4 kcal/mol.

  • 104. Gador, Niklas
    et al.
    Zhang, Bo
    Karlsson, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Hansson, Tony
    Dynamical interference structures in fully coupled bound-bound state quantum wave-packet dynamics2004Inngår i: Physical Review A, Vol. 70, nr 3, s. 033418-Artikkel i tidsskrift (Fagfellevurdert)
  • 105.
    GARCIA, JR
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    CEBRAL, JR
    SCOCCIMARRO, ER
    WAHNON, P
    ARENA, R
    BAZTERRA, V
    PELLIZZA, L
    RISI, A
    RODRIGUEZ, ML
    ZIMMERMANN, M
    A CATALOG OF VARIABLE-STARS IN THE LOWER INSTABILITY STRIP1995Inngår i: ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, ISSN 0365-0138, Vol. 109, nr 2, s. 201-262Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Identifications, positions, photometry, spectra, some pulsational features, other astrophysical parameters and literature for 302 pulsating variable stars in the lower instability strip, near the ZAMS, are given. About 185 stars have near homogeneous phot

  • 106.
    Gauld, JW
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Eriksson, LA
    Oxidative degradation of pyruvate formate-lyase2000Inngår i: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, ISSN 0002-7863, Vol. 122, nr 9, s. 2035-2040Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction mechanisms of oxidative degradation of the anaerobic radical enzyme pyruvate formatelyase (PFL) have been examined at the theoretical hybrid Hartree-Fock/density functional theory level B3-LYP. It is concluded that the most likely scenario in

  • 107.
    Goscinski, O
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Hagg, L
    The maximum entropy method and relaxation for multiple collisions involving highly charged ions1996Inngår i: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, ISSN 0020-7608, Vol. 58, nr 6, s. 689-698Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Advantages and disadvantages of the maximum entropy method (MEM) in application to the theory of relaxation are studied. The time evolution of distributions and of associated moments must obey stringent conditions for both finite and infinite intervals. T

  • 108.
    Hedstrom, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Deumens, E
    Ohrn, Y
    Electron nuclear dynamics of charge-transfer collisions of protons with atomic oxygen1998Inngår i: PHYSICAL REVIEW A, ISSN 1050-2947, Vol. 57, nr 4, s. 2625-2628Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The electron nuclear dynamics theory is applied to the study of proton collisions with ground-state oxygen atoms at collision energies of 0.5, 1.0, and 1.5 keV. Total electron transfer cross sections are calculated in reasonable agreement with recent expe

  • 109.
    Hedstrom, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Morales, JA
    Deumens, E
    Ohrn, Y
    Electron nuclear dynamics of H++H2O collisions1997Inngår i: CHEMICAL PHYSICS LETTERS, ISSN 0009-2614, Vol. 279, nr 3-4, s. 241-246Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Proton water collisions at 46 eV in the center of mass frame are studied within the electron nuclear dynamics theory (END). The electronic degrees of freedom are described with a coherent state formulation of determinantal wavefunctions. The nuclei are tr

  • 110.
    Hedström, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Salhi-Benachenhou, Nessima
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Calais, Jean-Louis
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Nonlinear optical properties of some substituted biphenyls1994Inngår i: Molecular Engineering, ISSN 0925-5125, E-ISSN 1572-8951, Vol. 3, nr 4, s. 329-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of donor-acceptor substituted biphenyls is examined using semiempirical SCF-MO methods. The geometries, dipole moments and first hyperpolarizabilities are obtained from AM1, MNDO and PM3 calculations. The finite-field method is used to calculate the polarizabilities. The properties of the substituents and the torsion angle between the phenyl rings are of fundamental importance for the hyperpolarizabilities. Among the three methods, AM1 leads to torsion angles closest to the experimental data. For each molecule, the HOMO is found to be localized on the donor part to some extent, whereas the LUMO is more concentrated on the acceptor part. The spectroscopic properties of the molecules are investigated using the ZINDO model. For all the molecules considered, the transition from the HOMO to the LUMO is found to be the most important for charge transfer, and this transition has been used in a two-state model to compute the first hyperpolarizability.

  • 111.
    Henningsson, Anders
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Stashans, A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Sandell, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Södergren, Sven
    Lindström, H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Vayssieres, L.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Lunell, Sten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Quantum Chemistry. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Siegbahn, Hans
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen, Fysik I.
    Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semi-empirical calculations2004Inngår i: Advances in Quantum Chemistry, ISSN 0065-3276, E-ISSN 2162-8815, Vol. 47, s. 23-36Artikkel i tidsskrift (Fagfellevurdert)
  • 112.
    Hessmo, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Quantum optics in constrained geometries2000Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    When light exhibits particle properties, and when matter exhibits wave properties quantum mechanics is needed to describe physical phenomena.

    A two-photon source produces nonmaximally entangled photon pairs when the source is small enough to diffract light. It is shown that diffraction degrades the entanglement. Quantum states produced in this way are used to probe the complementarity between path information and interference in Young's double slit experiment.

    When two photons have a nonmaximally entangled polarization it is shown that the Pancharatnam phase is dependent on the entanglement in a nontrivial way. This could be used for implementing simple quantum logical circuits.

    Magnetic traps are capable of holding cold neutral atoms. It is shown that magnetic traps and guides can be generated by thin wires etched on a surface using standard nanofabrication technology. These atom chips can hold and manipulate atoms located a few microns above the surface with very high accuracy. The potentials are very versatile and allows for highly complex designs, one such design implemented here is a beam splitter for neutral atoms. Interferometry with these confined de Broglie is also considered. These atom chips could be used for implementing quantum logical circuits.

  • 113.
    Hessmo, Björn
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Quantal phase for nonmaximally entangled photons2000Inngår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 62, nr 6, s. 062301-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We calculate the Pancharatnam phase difference obtained when entangled two-photon states interfere. This phase depends nontrivially on the degree of entanglement between the photons forming the two-photon state. We outline an experiment where the entanglement dependence of the two-photon phase may be studied interferometrically. Also we propose how a cyclic version of this phase may be useful for implementing an efficient quantum gate.

  • 114.
    Himo, F
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Babcock, GT
    Eriksson, LA
    Conformational analysis of quinone anion radicals in photosystem II and photosynthetic bacteria1999Inngår i: JOURNAL OF PHYSICAL CHEMISTRY A, ISSN 1089-5639, Vol. 103, nr 19, s. 3745-3749Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Using density functional theory (DFT) techniques, we have investigated possible conformers of the radical anions of plastoquinone (psQ), ubiquinone (ubQ), and menaquinone (mnQ), which are formed in the reaction centers of photosynthetic bacteria, blue-gre

  • 115.
    Himo, F
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Babcock, GT
    Eriksson, LA
    Tyrosyl radical in galactose oxidase not strongly perturbed by cysteine cross-link1999Inngår i: CHEMICAL PHYSICS LETTERS, ISSN 0009-2614, Vol. 313, nr 1-2, s. 374-378Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Several density functional methods are applied to calculate the hyperfine coupling constants and spin population distributions of sulfur-substituted and unsubstituted tyrosyl radical. The cysteine-substituted tyrosyl radical is found at the active site of

  • 116.
    Himo, F
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Eriksson, LA
    On the local structure of the glycyl radical in different enzymes1998Inngår i: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, ISSN 0300-9580, nr 2, s. 305-308Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Full hyperfine coupling tensors are computed for different geometric conformers of the glycyl radical, using gradient corrected Density Functional Theory (DFT) together with large basis sets (IGLO-III). Comparison is made with three enzymes in which the r

  • 117.
    Himo, F
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Eriksson, LA
    Institutionen för kvantkemi.
    Blomberg, MRA
    Siegbahn, PEM
    Substituent effects on OH bond strength and hyperfine properties of phenol, as model for modified tyrosyl radicals in proteins2000Inngår i: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, ISSN 0020-7608, Vol. 76, nr 6, s. 714-723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional theory is used to investigate the effects of a variety of substituents (CH3, OH, OCH3, SH, SCH3, NH2, NMe2, NO2, F, Cl, CN, and imidazole) on the phenol O-H bond dissociation energy (BDE) and phenoxyl radical hyperfine properties. Subst

  • 118.
    Himo, F
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen.
    Eriksson, LA
    Institutionen för kvantkemi.
    Maseras, F
    Siegbahn, PEM
    Catalytic mechanism of galactose oxidase: A theoretical study2000Inngår i: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, ISSN 0002-7863, Vol. 122, nr 33, s. 8031-8036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density functional methods, alone and together with molecular mechanics, are used to study the catalytic mechanism of galactose oxidase. This enzyme catalyzes the conversion of primary alcohols to the corresponding aldehydes, coupled with reduction of dio

  • 119.
    Hjelte, Ingela
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Piancastelli, M. N.
    Jansson, Carl Magnus
    Wiesner, Karroline
    Björneholm, Olle
    Bässler, M.
    Sorensen, S. L.
    Svensson, Svante
    Evidence of Ultra-Fast Dissociation in Ammonia Observed by Resonant Auger Electron Spectroscopy2003Inngår i: Chemical Physics Letters, ISSN 0009-2614, Vol. 370, s. 781-788Artikkel i tidsskrift (Fagfellevurdert)
  • 120.
    HUANG, MB
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    SUTER, HU
    ENGELS, B
    PEYERIMHOFF, SD
    LUNELL, S
    MULTIREFERENCE CONFIGURATION-INTERACTION AND DENSITY-FUNCTIONAL STUDY OF THE AZETIDINE RADICAL-CATION AND THE NEUTRAL AZETIDIN-1-YL RADICAL1995Inngår i: JOURNAL OF PHYSICAL CHEMISTRY, ISSN 0022-3654, Vol. 99, nr 24, s. 9724-9729Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The geometry and the hyperfine structure of the four-membered rings azetidin-1-yl radical (C3H6N) and azetidine radical cation (C3H6NH+) have been studied. The geometries of both molecules were optimized using Moller-Plesset perturbation theory as well as

  • 121.
    Hyllus, Philipp
    et al.
    Institut für Theoretische Physik, Universität Hannover, Germany.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Comment on `Complementarity between Local and Nonlocal Topological Effects'2002Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 89, nr 19, s. 198901-Artikkel i tidsskrift (Annet vitenskapelig)
  • 122.
    Hyllus, Philipp
    et al.
    Institut für Theoretische Fysik, Universität Hannover, Germany.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Precession and interference in the Aharonov-Casher and scalar Aharonov-Bohm effect2003Inngår i: Foundations of physics, ISSN 0015-9018, E-ISSN 1572-9516, Vol. 33, nr 7, s. 1085-1105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ideal scalar Aharonov-Bohm (SAB) and Aharonov-Casher (AC) effect involve a magnetic dipole pointing in a certain fixed direction: along a purely time dependent magnetic field in the SAB case and perpendicular to a planar static electric field in the AC case. We extend these effects to arbitrary direction of the magnetic dipole. The precise conditions for having nondispersive precession and interference effects in these generalized set ups are delineated both classically and quantally. Under these conditions the dipole is affected by a nonvanishing torque that causes pure precession around the directions defined by the ideal set ups. It is shown that the precession angles are in the quantal case linearly related to the ideal phase differences, and that the nonideal phase differences are nonlinearly related to the ideal phase differences. It is argued that the latter nonlinearity is due the appearance of a geometric phase associated with the nontrivial spin path. It is further demonstrated that the spatial force vanishes in all cases except in the classical treatment of the nonideal AC set up, where the occurring force has to be compensated by the experimental arrangement. Finally, for a closed space-time loop the local precession effects can be inferred from the interference pattern characterized by the nonideal phase differences and the visibilities. It is argued that this makes it natural to regard SAB and AC as essentially local and nontopological effects.

  • 123.
    Itagaki, Y.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi. Fysiska institutionen. Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Wang, P.
    Isamoto, N.
    Shiotani, M.
    Hasegawa, A.
    Jansson, M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi. Fysiska institutionen. Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Lunell, S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi. Fysiska institutionen. Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Static and dynamic structures of halogenated dimethyl ether radical cations: An EPR and MO Study2002Inngår i: Phys. Chem. Chem. Phys., Vol. 4, s. 2524-2529Artikkel i tidsskrift (Fagfellevurdert)
  • 124.
    Itagaki, Yoshiteru
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Wang, Peng
    Isamoto, Nobuyuki
    Shiotani, Masaru
    Hasegawa, Akinori
    Jansson, Carl Magnus
    Lunell, Sten
    Static and Dynamic Structure of Halogenated Dimethyl Ether Radical Cation: An EPR and MO Study2002Inngår i: Physical Chemistry Chemical Physics, ISSN 1463-9076, Vol. 4, nr 12, s. 2524-2529Artikkel i tidsskrift (Fagfellevurdert)
  • 125.
    Jansson, Carl Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Larsson, Per-Erik
    Salhi-Benachenhou, Nessima
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Bergson, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Lunell, Sten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Theoretical Calculations of Kinetic Isotope Effects for a Series of Aziridines2004Inngår i: Fundamental World of Quantum Chemistry: A Tribute to the Memory of Per-Olov Löwdin, Volume 3 / [ed] Brändas, Erkki J. and Kryachko, Eugene S., Dordrecht: Kluwer Academic Publishers , 2004Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The nitrogen inversion in aziridine and som parent substituted aziridines is investigated using various computational methods. The stationary points on each potential energy surface are optimized using the B3LYP functional of density functional theory (DFT) in conjuction with the popular 6-31G(d) basis set. Rate constants and thereby kinetic isotope effects (KIEs) are computed at different temperatures using transiton state theory (TST) and various techniques of variational transition state theory (VTST). Moreover, corrections are made for tunneling and non-classical reflection, using three semiclassic correction methods: the Wigner tunneling correction as well as the zero-curvature and the samll-curvature corrections. The performance of the various methods to compute KIEs are compared and the effects of tunneling are discussed.

  • 126.
    Jansson, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Quantum Chemical Calculations on ESR, Core Excitations, and Isotope Effects in Molecular Systems2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this thesis, quantum chemical calculations are undertaken mostly in order to interpret experimental results, but also to learn about computational techniques, their performance and their limitations. In paper I, the ionization-cleavage process of alkenes is investigated and two pathways are followed, one of initial cleavage and subsequent ionization and on the opposite, the other one of initial ionization and subsequent cleavage. The calculations reveal that ionization is best described by a vertical process, which is much faster than the relaxation of the molecule to its ionized structural minimum. Further, in paper II, the core hole excited state of ammonia is investigated and found to dissociate in an ultra-fast manner nicely explained by the calculated potential energy surface showing a very low barrier for dissociation. In paper III, the static and dynamic structures of two halogenated dimethyl ether radical cations are studied in ESR experiments, and it is found that, while the chlorinated molecule remains unaffected, the fluorinated molecule undergoes a dissociation or association reaction before the measurement takes place, the resulting fragments are searched for but not identified decisively. In paper IV, the stability of Jahn-Teller distorted selectively deuteriated benzene radical cation isotopomers is investigated by ESR experiments and density functional theory calculations. The temperature dependence, between 4.2 K and 77 K, of the ESR spectra is explained. Finally, in paper V, the hydrogen inversion in aziridine and methyl and dimethyl substituted aziridines is investigated. The rate constants and kinetic isotope effects are calculated using various techniques of transition state theory and tunneling correction methods.

    Delarbeid
    1. Cleavage of Neutral Alkenes and Alkene Radical Cations: Hybrid Hartree-Fock/Density Functional Theory Results
    Åpne denne publikasjonen i ny fane eller vindu >>Cleavage of Neutral Alkenes and Alkene Radical Cations: Hybrid Hartree-Fock/Density Functional Theory Results
    1998 Inngår i: Canadian Journal of Chemistry, ISSN 0008-4042, Vol. 76, s. 1817-1826Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91647 (URN)
    Tilgjengelig fra: 2004-04-15 Laget: 2004-04-15bibliografisk kontrollert
    2. Evidence of Ultra-Fast Dissociation in Ammonia Observed by Resonant Auger Electron Spectroscopy
    Åpne denne publikasjonen i ny fane eller vindu >>Evidence of Ultra-Fast Dissociation in Ammonia Observed by Resonant Auger Electron Spectroscopy
    Vise andre…
    2003 Inngår i: Chemical Physics Letters, ISSN 0009-2614, Vol. 370, s. 781-788Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91648 (URN)
    Tilgjengelig fra: 2004-04-15 Laget: 2004-04-15bibliografisk kontrollert
    3. Static and Dynamic Structure of Halogenated Dimethyl Ether Radical Cation: An EPR and MO Study
    Åpne denne publikasjonen i ny fane eller vindu >>Static and Dynamic Structure of Halogenated Dimethyl Ether Radical Cation: An EPR and MO Study
    Vise andre…
    2002 Inngår i: Physical Chemistry Chemical Physics, ISSN 1463-9076, Vol. 4, nr 12, s. 2524-2529Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91649 (URN)
    Tilgjengelig fra: 2004-04-15 Laget: 2004-04-15bibliografisk kontrollert
    4. Isotope Effects on the Jahn-Teller Distortion of Partially Deuteriated Benzene Cation Radicals: An Experimental and Theoretical Density Functional Theory Study
    Åpne denne publikasjonen i ny fane eller vindu >>Isotope Effects on the Jahn-Teller Distortion of Partially Deuteriated Benzene Cation Radicals: An Experimental and Theoretical Density Functional Theory Study
    Vise andre…
    2004 Inngår i: Physical Chemistry Chemical Physics, ISSN 1463-9076, Vol. 6Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-91650 (URN)
    Tilgjengelig fra: 2004-04-15 Laget: 2004-04-15bibliografisk kontrollert
    5. Theoretical Calculations of Kinetic Isotope Effects for a Series of Aziridines
    Åpne denne publikasjonen i ny fane eller vindu >>Theoretical Calculations of Kinetic Isotope Effects for a Series of Aziridines
    Vise andre…
    2004 (engelsk)Inngår i: Fundamental World of Quantum Chemistry: A Tribute to the Memory of Per-Olov Löwdin, Volume 3 / [ed] Brändas, Erkki J. and Kryachko, Eugene S., Dordrecht: Kluwer Academic Publishers , 2004Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The nitrogen inversion in aziridine and som parent substituted aziridines is investigated using various computational methods. The stationary points on each potential energy surface are optimized using the B3LYP functional of density functional theory (DFT) in conjuction with the popular 6-31G(d) basis set. Rate constants and thereby kinetic isotope effects (KIEs) are computed at different temperatures using transiton state theory (TST) and various techniques of variational transition state theory (VTST). Moreover, corrections are made for tunneling and non-classical reflection, using three semiclassic correction methods: the Wigner tunneling correction as well as the zero-curvature and the samll-curvature corrections. The performance of the various methods to compute KIEs are compared and the effects of tunneling are discussed.

    sted, utgiver, år, opplag, sider
    Dordrecht: Kluwer Academic Publishers, 2004
    Emneord
    Aziridnie, nitrogen inversion, kinetic isotope, effect, density functional theory calculations, variational transition state theory, Wigner-tunneling correction, zero-curvature tunneling correction, small-curvature tunneling correction
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-91651 (URN)978-1-4020-2583-9 (ISBN)978-90-481-6687-9 (ISBN)
    Tilgjengelig fra: 2004-04-15 Laget: 2004-04-15 Sist oppdatert: 2011-04-09bibliografisk kontrollert
  • 127.
    Johansson, Niklas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Optimal topological test for degeneracies of real Hamiltonians2004Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, nr 6, s. 060406-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider adiabatic transport of eigenstates of real Hamiltonians around loops in parameter space. It is demonstrated that loops that map to nontrivial loops in the space of eigenbases must encircle degeneracies. Examples from Jahn-Teller theory are presented to illustrate the test. We show furthermore that the proposed test is optimal.

  • 128.
    Johansson, Niklas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för teoretisk fysik.
    Sjöqvist, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Searching for degeneracies of real Hamiltonians using homotopy classification of loops in SO(n)2005Inngår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 71, nr 1, s. 012106-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Topological tests to detect degeneracies of Hamiltonians have been put forward in the past. Here, we address the applicability of a recently proposed test [Phys. Rev. Lett. 92, 060406 (2004)] for degeneracies of real Hamiltonian matrices. This test relies on the existence of nontrivial loops in the space of eigenbases SO$(n)$. We develop necessary means to determine the homotopy class of a given loop in this space. Furthermore, in cases where the dimension of the relevant Hilbert space is large the application of the original test may not be immediate. To remedy this deficiency, we put forward a condition for when the test is applicable to a subspace of Hilbert space. Finally, we demonstrate that applying the methodology of [Phys. Rev. Lett. 92, 060406 (2004)] to the complex Hamiltonian case does not provide any new information.

  • 129.
    Jonsell, S
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Monkhorst, HJ
    Effects from changes in the final state spectrum on the neutrino mass determination from T-2 beta decay experiments1996Inngår i: PHYSICAL REVIEW LETTERS, ISSN 0031-9007, Vol. 76, nr 24, s. 4476-4479Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Some improvements in the final state spectrum of T-2 beta decay are discussed. Their importance for neutrino mass determination has been estimated through numerical experiments. Results depend most strongly on the length of the energy interval of the expe

  • 130.
    Jonsell, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Exotic states of matter: Molecular effects in investigations of weak, strong, and long-range forces1999Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Some cases in which the interpretation of experiments in nuclear, particle, and low temperature physics requires understanding of molecular effects have been studied.

    Neutrino-mass determination from β decay of T2 requires knowledge of the energy loss due to molecular excitations of the daughter HeT+ molecule. The theoretical final-state distribution has been studied, in particular the role of nonadiabatic effects. Possible origins of unphysical experimental results leading to a "negative mass squared" are discussed, as are various methods for experimental verification of the final-state distribution.

    Pionic hydrogen (pπ-) is used in experiments that determine the mass difference mπ- - m<SUB>p0, and other fundamental properties of pions. Formation of three-body resonances (ppπ-)* in the cascade of pionic hydrogen atoms has been studied. The decay of these state provides an efficient accelerationmechanism for the pionic atoms, with impact on the experimental analysis.

    Cold antihydrogen will be used at CERN to study the CPT theorem and the weak equivalence principle. We study the collisional interaction of antihydrogen with ultracold hydrogen. It has been found that cooling dominates over annihilation at antihydrogen temperatures down to ~ 0.1 K.

    In Bose-Einstein condensation of atomic hydrogen the shape of the 1s-2s line is used to probe the temperature and density. Long-range interactions between excited 2s atoms have been studied in order to improve the understanding of line shapes above and below the condensation temperature.

  • 131. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Low energy hydrogen-antihydrogen collisions2000Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 663-664, s. 959C-962CArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ground-state interaction potential between hydrogen and antihydrogen has been calculated within the Born-Oppenheimer approximation. Cross sections for rearrangement and annihilation in flight have been determined. Implications for cooling of antihydro

  • 132. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Neutrino-mass determination from tritium beta decay: Corrections to and prospects of experimental verification of the final-state spectrum1999Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 60, nr 3, s. 34601-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    We have investigated the final-state spectrum of HeT+ and HeH+ following beta decay of T-2 or TH. For the electronically bound-state part of the spectrum the effects of a corrected recoil, improved potential curves for the excited states, nonadiabatic eff

  • 133. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Non-adiabatic couplings between the final states of tritium beta decay1998Inngår i: Polish Journal of Chemistry, ISSN 0137-5083, Vol. 72, nr 7, s. 1323-1333Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The non-adiabatic couplings between the ground state and the first 5 excited states in (HeT+)-He-3 have been calculated. Non-adiabatic corrections to the beta-decay spectrum of T-2 are derived in first-order perturbation theory. These corrections are esti

  • 134. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Forrey, Robert
    Cote, Robin
    Dalgarno, Alex
    Long-Range Interactions between Two 2s Excited Hydrogen Atoms2002Inngår i: Phys. Rev. A, Vol. 65, s. 042501-Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 135. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Fysiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Kvantkemi.
    Zygelman, Bernard
    Dalgarno, Alex
    Stability of hydrogen-antihydrogen mixtures at low energies2001Inngår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 64, nr 5, s. 052712-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stability of antimatter in contact with matter has been investigated. The interaction between hydrogen and antihydrogen is considered as the prototype reaction. We have focused interest on the rates for proton-antiproton and/or electron-positron annih

  • 136. Jonsell, Svante
    et al.
    Wallenius, Jan
    Froelich, Piotr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    The Influence of pp pi ions on pion absorption in H-21999Inngår i: PHYSICAL REVIEW A, ISSN 1050-2947, Vol. 59, nr 5, s. 3440-3453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The existence of three-body resonances in the molecular ion pp pi has been shown by means of a variational calculation in Jacobi coordinates. The relativistic and strong-force corrections to the Coulombic binding energies and the decay widths of the reson

  • 137.
    JURIMAE, T
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    STRANDBERG, M
    KARELSON, M
    CALAIS, JL
    A SEMIEMPIRICAL STUDY OF HETEROCYCLE OLIGOMERS AND POLYMERS IN DIFFERENT DIELECTRIC MEDIA1995Inngår i: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, ISSN 0020-7608, Vol. 54, nr 6, s. 369-379Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Four common five-membered heterocycles-pyrrole, phosphole, thiophene, and furan- and their oligomers with the chain length of 2, 4, 6, and 10 units have been studied quantum chemically using the semiempirical PM3 parameterization. The oligomers of pyrrole

  • 138.
    Karis, O
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Hernnas, B
    Puglia, C
    Nilsson, A
    Martensson, N
    Edvardsson, D
    Lunell, S
    Manifestation of the paramagnetic splitting of physisorbed O-2 in core and valence spectroscopies1996Inngår i: SURFACE SCIENCE, ISSN 0039-6028, Vol. 352, s. 511-517Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    We have investigated the core excited sigma* resonance region in 1 monolayer of O-2, physisorbed on several substrates. Comparisons with the paramagnetic splitting obtained in X-ray photoelectron spectroscopy (XPS) and in ultraviolet photoelectron spectro

  • 139.
    Karlsson, EB
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Brändas, E
    Modern studies of basic quantum concepts and phenomena1998Inngår i: PHYSICA SCRIPTA, ISSN 0281-1847, Vol. T76, s. 7-15Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    This is a short summary of the purpose and the contents of the Nobel Symposium. It serves as an introduction to the original papers presented by the participants. The topics are hem organized in a way that does not necessarily follow the order of presenta

  • 140.
    Karlsson, Hans
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Goscinski, Osvaldo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för kvantkemi.
    Correlation functions and thermal rate constants2001Inngår i: Journal of Physical Chemistry A, Vol. 105, nr 12, s. 2599-2603Artikkel i tidsskrift (Fagfellevurdert)
  • 141.
    Karlsson, Hans O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Dynamics of hydrogenic wave packets in electric and magnetic fields1994Inngår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 50, nr 5, s. 3787-3792Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The survival probability P(t) of hydrogenic wave packets for some choices of strong external electric and magnetic fields is studied. The recursive residue generation method, in combination with complex dilation and a Laguerre basis, is used to calculate the local density of states from which P(t) is computed via a Fourier transform. P(t) is calculated both for a single initial ‖8p0〉 state and for an initial radial hydrogenic wave packet centered around n=15. In the first case only, in principle, a single n manifold is involved in the dynamics, while in the latter case several n manifolds contribute. The different choices of initial states lead to significantly different results. The choice of fields was made in order to exemplify various patterns of behavior. Results similar to those obtained here were found in recent experiments by Broers and co-workers [Phys. Rev. Lett. 71, 344 (1993); Phys. Rev. A 49, 2498 (1994)]. The results presented in this work are quantum-mechanical calculations of hydrogenic wave packets in strong fields that include the effect of finite lifetimes on P(t).

  • 142.
    Karlsson, Hans O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Exterior complex dilation for grid methods: Application to the cumulative reaction probability1998Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 108, nr 10, s. 3849-3853Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exterior complex dilation (ECD) is introduced for the discrete variable representation (DVR) via a general coordinate mapping. The procedure leads to a computationally efficient and easily implemented approach for imposing outgoing boundary conditions, comparable with absorbing potentials in terms of minimizing the grid and parameters used. ECD relies on a rigorous mathematical framework in contrast to absorbing potentials. The DVR-ECD approach is illustrated by computation of the cumulative reaction probability for the H+H-2 reaction in one and two dimensions.

  • 143.
    Karlsson, Hans O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Lanczos algorithms and cross correlation functions2003Inngår i: Journal of Theoretical and Computatational Chemistry, Vol. 2, nr 4, s. 523-Artikkel i tidsskrift (Fagfellevurdert)
  • 144.
    Karlsson, Hans O
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Predissociation resonances in CO and IBr: Smooth exterior scaling combined with the discrete variable representation2000Inngår i: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 11, nr 2, s. 207-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Smooth exterior scaling (SES) and the discrete variable representation (DVR) are combined to accurately compute predissociation resonances of a bound state non-adiabatically coupled to a dissociative state. For the CO(B(1)Sigma(+)-D('1)Sigma(+)) predissociation interaction good agreement is found with approaches based on optical potentials and complex scaling. The comparison is done both in the diabatic and the adiabatic representation. The effect of the coupling strength in the IBr (B(3)Pi(0+)-Y0(+)) predissociation interaction and the transition from the diabatic to the adiabatic picture was studied by computing resonances for coupling strengths from 50 cm(-1) up to 300 cm(-1). The transition from weak (diabatic) to strong (adiabatic) coupling was clearly seen. The intermediate case leads to a complicated resonance distribution. Comparison was made with recent studies using pump-probe spectroscopy [M. Shapiro, M.J.J. Vrakking, A. Stolow, J. Chem. Phys. 110, 2465 (1999)]. It was found that the overall features of the experiment could be explained from the resonance distribution, but for a detailed comparison more accurate potential energy surfaces and couplings are needed.

  • 145.
    Karlsson, Hans O
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Bendazzoli, GL
    Goscinski, Osvaldo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Evangelisti, S
    Density of states of alternant cyclic polyenes (CH)(N) by a direct Lanczos method1997Inngår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 63, nr 3, s. 719-728Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A direct full configuration interaction approach, previously used for studying individual low-lying eigenvalues, is combined with iterative Lanczos calculations, in order to obtain global properties of large Hermitean Hamiltonian matrices. To this effect systematic generation of random start vectors is used to compute statistical approximations to the density of states (DOS). Applications for cyclic polyenes in order to illustrate the viability of the scheme modeled by correlated, tight-binding Pariser-Parr-Pople (PPP) Hamiltonians of increasing complexity are presented. The degree of correlation in the solutions is controlled by the parameter beta. Convergence properties of the DOS for N=10 and N=14 are studied varying the extent of correlation.

  • 146.
    Karlsson, Hans O
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Goscinski, Osvaldo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    A direct recursive residue generation method: application to photoionization of hydrogen in static electric fields1994Inngår i: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 27, nr 6, s. 1061-1072Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In studies of hydrogenic systems via the recursive residue generation method (RRGM) the major bottleneck is the matrix vector product HC, between the Hamiltonian matrix H and a Lanczos vector C. For highly excited states and/or strong perturbations the size of H grows fast leading to storage problems. By making-use of direct methods, i.e. avoidance of explicit construction on of large Hamiltonian matrices, such problems can be overcome. Utilizing the underlying analytical properties of the Laguerre basis e(-lambdar)L(k)2I+2(2lambdar) a direct RRGM (D-RRGM) for the unperturbed hydrogenic Hamiltonian is derived, changing the storage needs from scaling as N2 to 4N where N is the number of radial functions for each factorized H-0(l, m) block with the possibility of parallel processing. A further computational simplification is introduced by putting the expression for the photoionization (PI) cross section in the rational form conventionally used in the representation of density or states (DOS). This allows the construction of the PI cross section directly from the tridiagonal Lanczos matrix avoiding the explicit calculation of individual eigenvalues and eigenvectors. To illustrate and verify the method the PI cross section for a hydrogen atom in a static electric field, for both pi and cr polarization, was calculated for an electric field strength of F = 5714 V cm-1. Sufficiently large basis sets could be employed so that good comparison with experiment and other theoretical work was obtained, including the field-induced modulations near the zero-field ionization limit.

  • 147.
    Karlsson, Hans O
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.
    Goscinski, Osvaldo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kvantkemi.