CV

Physics for Engineers undergrad. level - “IT program at Chalmers” (Lecturing and problem solving)

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Physics for Engineers undergrad. level - “IT program at Chalmers” (Lecturing and problem solving)

DISSERTATIONS

I have been in the committee of the following dissertations and Licentiate thesis:

• - 1993
  PhD Thesis - “Calculations of Linear and Nonlinear Optical Properties of Ionic Crystal Surfaces and Fullerenes”
  by Erik Westin,
  Department of Physics, Chalmers University of Technology, Göteborg.

• - August 1994
  PhD Thesis - “Catalytic Reactions Studied with Metal-Oxide-Semiconductor Structures”
  by Joakim Fogelberg,
  Department of Physics, Linköping University, Linköping.

• - 1998
  PhD Thesis - “Model studies of water and small biomolecules at solid surfaces”
  by Patrik Löfgren,
  Department of Applied Physics, Chalmers University of Technology, Göteborg

• - March 1999
  PhD Thesis - “Efficient density-functional-based calculational methods for surfaces”
  by Lennart Bengtsson,
  Department of Applied Physics, Chalmers University of Technology, Göteborg

• - October 1998
  Licentiate Thesis - “Bulk and Surface Structure of Kappa-Alumina”
  by Carlo Ruberto,
  Department of Applied Physics, Chalmers University of Technology, Göteborg

• - November 1999
  PhD Thesis - “Dynamic effects in the interaction of charged particles with solids:
  energy losses in insulators and low energy electron lifetimes”
  by Enrique Zarate Larrinaga,
  The University of the Basque Country, San Sebastian, SPAIN

• - May 2000
  Licentiate Thesis - “Diffusion, Nucleation, and Island Growth in Metal-on-Metal Epitaxy”
  by Staffan Ovesson,
  Department of Applied Physics, Chalmers University of Technology, Göteborg.

• - October 2000
  Licentiate Thesis - “First-Princilpes Density-Functional Computational Experiments to Understand the Nature of Metal-Carbonitride Interface Adhesion”
  by Sergey Dudiy,
  Department of Applied Physics, Chalmers University of Technology, Göteborg.

• - June 2002
  Licentiate Thesis - “Experimental and theoretical investigation of two surface alloys: Al(100)-Na and Al(100)-Li”
  by Mikael Borg,
  Naturvetenskapliga fakulteten, Lunds Universitet, Lund.

• - January 31 2003
  Licentiate Thesis - “Aspects of the catalytic water production from first-principles calculations”
  by Gustav Karlberg,
  Department of Applied Physics, Chalmers University of Technology, Göteborg.

• - January 31 2003
  PhD Thesis - “Tuning the electrical and optical properties in low-dimensional structures”
  by Per Sundqvist,
  Physics and egineering of physics, Chalmers, Göteborg.

• - April 25 2003
  PhD Thesis - “From Oxygen to Oxide: First-Principles Study of Some Key Aspects”
  by Behrooz Razaznejad,
  Department of Applied Physics, Chalmers University of Technology, Göteborg.

• - september 2003
  PhD Thesis - “Electron-phonon interactions on metal surfaces”
  by Asier Eiguren,
  Department of Material Physics, University of San Sebastian, San Sebastian, Spain.

• - April 2 2004
  PhD Thesis - “Laser diagnostics and kinetic modelling of the reaction intermediates in catalytic combustion”
  by Åsa Johansson,
  Department of Physical Chemistry, Göteborg University, Göteborg.

• - April 29 2004
  PhD Thesis - “Electronic states of Adsorbates and Insulating Overlayers on Metal Surfaces”
  by Fredrik Olsson,
  Department of Applied Physics, Chalmers University of Technology, Göteborg.

SUPERVISION OF DIPLOMA WORKERS

I have formulated and supervised three diploma works for undergraduate students. The diploma work is compulsory for the diploma of Master of Science in Engineering at Chalmers University of Technology.

1. Aare Mällo -1984 worked with me on the problem of associative thermal desorption. We showed that a double peak structure in the thermal desorption spectra could be due to adsorbate-adsorbate interaction in contrast to the conventional interpretation of two adsorption sites. The work resulted in a publication [6].

2. Magnus Hurd -1987 studied a Langmuir-Hinshelwood type kinetic model for the catalytic reaction 2NO + 2H2 to N2 + 2H2O. He applied a computer program I developed for solving coupled rate equations (based on the multidimensional Newton Raphson method). The model was successful in reproducing the nitrogen production, when the initial sticking of NO and H2 were chosen to fit experimental results. It was concluded that water is formed by sequential addition of adsorbed atomic hydrogen.

3. Johan Carlsson -1997 “Theoretical Investigation of the Structural and Electronic properties of ZnO”. The structure and the electronic properties of ZnO was analyzed. The investigation was performed by ab initio plane wave calculations with the program package Insight II from Biosym Inc. The plane wave program was based on the local density approximation and the pseudo potential approach to solid state calculations. Surface atom relaxation was calculated using a super cell including bulk, surface and vacuum. Good agreement with earlier calculations and experimental LEED data.

4. Vasile Chis -2003 “First Principles Study of Surface Phonons of Metal Surfaces”. The phonon electron structure was studied applying the Density Functional Theory (DFT) based PWSCF code. Al(100) was investigated. Several localized phonon modes localized to the surface was found. Furthermore it was shown that the surface relaxation resulted in an outward displacement of the outermost surface layer. Due to the fact that the electron surface state penetrates deep into the bulk a slab of at least 20 layers has to be used in order to get a reasonable convergence with respect to phonon energies.

5. Tomas Petersson -2004 “CO - Quantum Dot intercation - A Newns Anderson Study of Charge transfer”.Applying the Newns Anderson model ther Charge transfer was invetsigated as a CO molecule approach a free electron Quantum Dot (QD). With the anti-bonding 2pi* LUMO orbital of CO as the adsorption level it was shown that quantum effects was present for the charge transfer as the QD radius was small. Having a QD with an electron density of bulk sodium the charge transfere was oscillating as a function of QD radius with a maximum for a 6 electron QD. The behaviour is due to the fact that CO molecule with its axis normal to the cylidrically shaped QD surface will only couple to the azimuthal quantum number m=-1 and m=+1.

6. Sriram Poyyapapakkam -2013 “First pronciples study of electronic and optical properties of biaxialy strained lanthanum nickelate” Strongly correlated metal oxide materials is an exotic class of compounds possible candidates for a number of applications especially in electronics and magnetic storage device applications. Some high Tc superconductors belongs to this category,a booming area of research today. Heterostructuring these oxide structures has led to realization of novel properties at the interfaces such as superconductivty and a two dimensional electron gas, not seen in the constitutent materials. One of the recently well studied metal-oxide structure is the LaNiO3/LaAlO3 superlattice. Lanthanum nickelate, LaNiO3 (LNO) is found to be in some extent analogous to cuprate superconductors and furthermore the only paramagnetic nickelate down to very low temparatures. The physics behind the properties of LNO is yet to be understood in detail in particular when it comes to lattice strain effects in ultra-thin LNO films. As a first step in an extended analysis of the electronic and optical properties of LNO, we perform first principle density functional theory (DFT) and linear response theory in the time dependent DFT formalism in order to find out about how much can be understood within a mean field description of the electron-electron interaction. Applying bilateral strain, changes in the low energy bandstructure was observed indicating charge transfer. This phenomena is referred to as self-doping, an interesting alternative to conventional chemical doping.

SUPERVISION OF Licentiate students

• Johan Carlsson Jan 1997 – 4 June 1999

  First-principles investigations of a metallic quantum well system - Na on Cu(111)

• Vanja Lindberg 2000-31 May 2002

  Electron structure of adsorbed Quantum Dots

• Vasile Chis 2004-2006

  Surface electron and phonon state phenomena

• Hugo Strand 2008 – 2011

  Strong correlation - DMFT model study

SUPERVISION OF PhD students

• Johan Carlsson 4 June 1999 – 15 March 2002

  A first principles Study of Interface Systems: Electronic properties of Metal Quantum Wells and Varistor Materials

• Vanja Lindberg 31 May 2002 – 1 April 2005

  Electron Structure and Reactivity of Adsorbed Metallic Quantum Dots

• Vasile Chis 2006 – 2009

  First principles surface phonons and overlayer electronic structure

• Hugo Strand 2008 – 2013

  Strong correlation - Models and Methods

PEDAGOGICAL TRAINING

The course “Supervising as a profession”, part I: 13-14 March 1995. held by J. Lindén, Lund University; part II: 9 Maj 1995, held by A. Mårtensson FU Chalmers University of Technology.

DEPARTMENT WORK, CONFERENCES AND NETWORKS

• Interface

  Organized a seminar serie, “Interface”, every second Tuesday at the department during 1992-1993. The “Interface” meeting was a successful forum for short presentations in the field of physics and physical chemistry, which served as an interface between experimentalists and theorists.

• Pedagogical Support for PhD Students

  From the fall of 1999 to the fall of 2002 I was as a Pedagogical Support for PhD Students at the Department Physics and Engineering Physics at Chalmers University. My duty was to:

  - make sure that the new PhD student is introduced about (i) teaching and pedagogical courses, (ii) the role of the pedagogical support person and (iii) the pedagogical network among the PhD students.

  - support the students pedagogical development, (i) discuss the teaching profile of the student and (ii) available pedagogical courses.

  - be a general support for the student and to be a link between the student and the teacher responsible for the course in which the student take part as a teacher.

  - establish a document for the student on the received level of pedagogical competence at the end of the PhD period.

• 24 November 1999 I was invited by the Stenungssunds kommun to give a seminar: “New Age and Quantum Physics”. The seminar was followed by a vivid discussion.

• 27 November 1999, during the national wide Popular-Science-week , I organized an “Open house”, were members of our group presented ongoing experimental and theoretical work for the public.

• Head of Department of Physics, Gothenburg University, Januray 2009- June 2013

**Norfa Network

Coordinator for the network “Quantum properties of nanostructures**“.
Financing from NorFa (2004-2006) 300.000 Nok/year

**Norfa Workshop

Organisor of the workshop “Quantum properties of nanostructures**“.
at Hjortviken 1-4 June 2004.
**
PROFESSIONAL ORGANIZATION**
American Physical Society.

LANGUAGE FACILITY
English: general fluency, French: some skill.

ACCOMPLISHMENTS
91 publications in international scientific journals.
40 presentations international conferences (25 oral and 15 posters),
( 9 of the oral presentations were invited talks).
18 invited seminars and visits.

PRINCIPAL RESEARCH INTEREST

• Vibrational and translational damping of molecules on metal surfaces.
  1980-1984

• Thermal desorption.
  1985-1986

• Methods to calculate the density matrix in Quantum Statistical Mechanics.
  1986-1989

• Modeling of surface reaction kinetics.

• Alkali metal promoted oxidation of semiconductors and semi-metals.
  1989-1993

• Charge transfer processes in adsorbate-metal interaction

• Dissociation mechanism for oxygen on metals.

• Photostimulated processes at metal surfaces.
  1993-

• ZnO Varistors-grain boundary physics.

• Quantum-well states in overlayers.

• first principles studies of alkali-overlayers on metals - Quantum-well states.
  1996-

• Electron Dynamics of surface-localized electron states of metals.

• ZnO Varistors-grain boundary physics.

• Nano Catalysis; Electron Structure and Reactivity of adsorbed metallic Quantum Dots.

• Strong coupling in correlated materials.

• Electron-phonon coupling (EPC) in graphen and other 2D materials such as LiBC; lifetime broadening and EPC constant.

SUMMARY OF RESEARCH PROGRESS
(indicated references are found in the “LIST OF PUBLICATIONS”)

• During my time as a graduate student, in the group of prof. B.I. Lundqvist, I investigated the electron-hole pair mechanism for the damping of vibrational and translational motion of adsorbates on metal surfaces [1-5,7,8]. This study, based on a “first principle” Density Functional calculation scheme, showed that the electronic mechanism could be important for light adsorbates. The characteristic isotope- and temperature dependence of this contribution to the observed vibrational line width was pointed out in order to distinguish it from the contribution from the competing phonon mechanism.

  Molecular dynamics calculations have shown that the related electronic friction is reasonable, when considering hydrogen diffusion on metals (G. Wahnström 1991). The first direct measurement of vibrational lifetimes (CO/Pt(111)) using subpicosecond transient IR spectroscopy (R. Cavanagh 1991), gave lifetimes of the same order of magnitude as we predicted. From the additionally observed weak temperature dependence, it is concluded that the electron-hole pair mechanism is in operation.

  The diploma worker (examens arbetare) Aare Mällo worked with me on the problem of associative thermal desorption. We showed that a double peak structure in the thermal desorption spectra could be due to adsorbate-adsorbate interaction in contrast to the conventional interpretation of two adsorption sites. The work resulted in a paper [6].

• As a Post.Doc. with prof. H. Metiu at the University of California in Santa Barbara, I developed methods for calculation of the density matrix [9-11]. The Fast Fourier Transform method (FFT), was found to be most efficient for the propagation of the density matrix in the imaginary time from the classical high temperature limit to an arbitrary low temperature. In the paper [11], I used FFT to solve the mixed real and imaginary time propagation, solving the Liouville’s equation to obtain the density matrix. In a model study, we applied this method to calculate the absorption line shape function considering a transition between two electronic states of a diatomic molecule in contact with a heat bath.

• During my stay in prof. B. Kasemos group I worked on two projects, (i) kinetic modeling of the catalytic water reaction on platinum [18,20,24,25], and (ii) alkali-metal-promotion of oxidation of graphite. In these projects I worked in close contact with experimentalists.

  In the first project, prof. A. Rosens group together with Kasemo made the measurements. We developed a kinetic model which could explain the observed temperature and H2/O2 mixture dependence of the hydroxyl and water production for intermediate total pressures (1-100 mtorr). With use of the kinetic model, we were able to extrapolate to higher pressures, where we predicted hydrogen poisoning of the surface.
  The computer program I developed for solving the coupled rate equations (based on the multidimensional Newton Raphson method) can more or less be used as a “black box” for an arbitrary reaction. This program has been used by the A. Rosens group to model the “back” decomposition reaction of water. It was also used by a diploma worker of mine, Magnus Hurd, to study the catalytic reaction 2NO + 2H2 to N2 + 2H2O reaction.

  In the second project, I worked primarily together with Peter Sjövall, who performed the experiments. The model I proposed could qualitatively and semi quantitatively explain the enormous increase of the oxidation rate of graphite, when small amounts of alkali atoms were preadsorbed. The model was based on the idea that as the alkali will cause an up-shift of the Fermi level (decrease of work function), there will be an increase of the charge transfer from the surface to an antibonding molecular orbital of the oxygen molecule, which will stimulate dissociation. The oxygen atoms will further easily react with the carbon atoms of the graphite surface.
  The basic ideas of this project lead me to further developed the model to study the observed alkali promoted oxidation of semiconductor surfaces [21,22].

  During this period of time I visited prof. V.P. Zhdanov at the Institute of Catalysis in Novosibirsk, USSR. Ever since, we have collaborated on different projects
  .

• The past year I have performed studies of the interaction between the oxygen molecule and metal surfaces [26,31]. In collaboration with S. Gao, I have used an embedding cluster scheme (S. Gao 1991) to study the electron structure of chemisorbed molecular oxygen on the metals. We observed strong shifts and broadenings of the chemically active molecular levels of oxygen and in connection with this, a significant donation of electron charge to the molecule from the surface. The results presented in [26,31] indicate that the qualitative difference, when the molecule interacts with a noble- or transition metal surface, is attributed to the different location of the d-band on the energy scale. The results are in qualitative agreement with experiments.

• In collaboration with Zhdanov, I have studied non-adiabatic effects in atom-metal surface scattering. These effects appear due to a finite velocity of the atom approaching the surface. We also investigated the effects of the intra-atomic coulomb repulsion on the charge transfer between the atom and the molecule.

  In agreement with experimental observations for Na scattering on a copper surface, at incoming kinetic energies of 10-100 eV, we have found that the intra-atomic coulomb repulsion will give rise to a relatively large probability of creating positive ions [27]. We hope to further develop this scheme of calculation to study possible non-adiabatic effects for the dissociation of diatomics, such as the oxygen molecule.

• By the beginning of 1992 I started to work in the field of surface photochemistry. I have investigated the direct mechanism for photoinduced desorption and dissociation of O2 on Pt(111) [28]. Information about the local density of states is obtained from an embedded cluster calculation scheme, the same as used in previous studies [26,31]. From an experimental point of view, different aspects of the cross section has been studied, by varying (i) photon frequency, (ii) polarization of the light, p- and s-polarized, and (iii) angle of incidence of the light. I found reasonable agreements with experiments considering, (i) the onset for the desorption and dissociation yields as a function of foton frequency and (ii) the angular dependencies of the cross sections for unpolarized light. However, polarized light experiments on the similar system O2/Pd(111) showed qualitatively different angular dependencies compared to the calculated ones. Furthermore, taking quenching into account, the calculated cross sections are 2-3 orders of magnitude less than experimentally measured. My conclusion was that the indirect, “hot electron”, mechanism probably dominates in the process. This conclusion was also supported by the experimental observation that the cross section for desorption and dissociation have similar angular dependence on the angle of incident light as the substrate absorbance.

• Photoinduced desorption and dissociation of O2 on metals. A theoretical model is developed in order to investigate the hot electron mechanism in photoinduced surface reactions. We applied the model to discuss the experimentally measured photoinduced desorption and dissociation of O2 on Pd(111) and Ag(110). The photo energy dependence of the cross section is in reasonable agreement with experiment [29,30]. In a separate paper we have analyzed the survival probability and in particular tried to explain why, according to experiments, this probablity seems to be larger than expected. For photoinduced dissociation of chemisorbed molecules, locking of vibrational excitations due to Franck-Condon factors, could take place in the electronically excited state. This will lead to an effective electron capture width which is relatively small [33].

• O2 dissociation on metals. In collaboration with prof. P. Nordlander and L. Lou, I am further investigating the chemisorption system O2 on metals. In the previous study [26,31], in collaboration with S. Gao, of chemisorbed O2 on Cu(100), Ni(100) and Pt(111), using a semi-empirical embedding scheme resulted in qualitatively different results in comparison with other investigations. The main difference was that we found the d-states of the transition metals to be most important, considering interaction and charge transfer. This is in clear contrast to quantum chemistry calculations. We have been studying the system O2 on copper and nickel clusters using first principles methods based on the Density Functional scheme with LDA. The total energies are calculated and in particular the restricted minimum energy path of the molecule is determined. The character of the molecule-cluster bond is investigated and a detailed mapping of the change of the bond structure which lead to dissociation as the molecule approach the cluster. Our first comparative study of molecular oxygen approaching a relatively small nickel and copper cluster is presented in the publication [34].

• Photoinduced desorption of potassium atoms from graphite. Photoinduced desorption of K from a graphite surface is investigate experimentally in Prof. B. Kasemos group working in our department. Detailed information is obtained, such as photoinduced desorption yield dependence on K-coverage, photon energy and polarization of the light. The results indicate that an indirect “hot electron” mechanism is in operation. In collaboration with the experimental group and Prof. V.P. Zhdanov several papers have been accepted for publication [28, 29, 30, 32, 33, 35, 36, 37].

• Electron structure of K/Graphite. First principles electron structure calculations of the system potassium on graphite. This is a collaboration with L. Lou, Wavefunction Irvine, California and presently with L. Österlund, Competence Centre for Catalysis at Chalmers. This mainly theoretical investigation is stimulated by our earlier results from the photo experiment [32,35,36,37]. Important issues that we have focused on are, (i) potassium induced electron structure, (ii) the degree of charge transfer from potassium to the graphite surface as a function of potassium coverage, (iii) barriers for potassium diffusion along the graphite surface and into the bulk of graphite (intercalation) and (iv) structural phase transition. Recent resluts are reported in the publications [39,42].

PRESENT AND FUTURE PROJECTS

• Experimental and theoretical investigation of the ZnO grain boundaries
  Me and Eva Olsson at the Department of Physics at Chalmers University of Technology propose a project devoted to a study of the basic physics underlying the operation of the ZnO varistor (see a separate NFR application). The project is based on a unique collaboration between experiment-theory-industry. The clear and applied aims raised by the industry ABB Switchgear AB in Lundvika is to find the key parameters responsible for the non-linear IV characteristics, in order to optimize the varistor function.
  We will investigate the influences on the IV characteristics, referring to (i) crystal surface orientations at the grain boundary and (ii) inter facial impurities. This basic experimental and theoretical research regarding the grain boundaries is also of interest in a broader sense, e.g. for the understanding of high temperature super conductors.
  Since January 1997 I have a student working on electron structure calculations on ZnO. He has produced a Diploma Thesis (supervised by me) “Theoretical Investigation of the Structural and Electronic properties of ZnO”.
  During a two month stay, August and September year 2000 at the University of Cambridge Johan has started up a collaboration with the group of Paul Bristow, head of the department of Material Science and Metallurgy. We shear a common interest to perform first principles studies of ZnO grain boundaries (GB). This collaboration has been very fruitful end covers studies of GB doping by Sb and Bi doping as well as incorporating Zn vacancies and O interstitials [44,45,46,48,51,52,54]. Bi doping at reasonable concentrations form donor states in the ZnO bandgap and the complex including Bi doping, Zn vacancies and O interstials form acceptor states. In the latter case the Double Shottky Barrier model applies and the ZnO non-linear characteristics could be explained

• Electronic Structure and Reactivity of Quantum Dots My PhD student Vanja Lindberg has performed a model study of a cylindrical quantum dot (QD) [43,49] and is now working with collaborators in professor Risto Nieminens group in Helsinfors. We are performing first principle DFT calculation of a cylindrical quantum dot applying the MIKA real-space code [55]. One of the more important issues is to investigate how an adsorbed molecule on the QD will be influenced by the size of the dot. In particular, the dot-size-dependence of activation barrier and chemical bonding is of interest.

• Hole lifetime of quantum well states in alkali overlayers on metals.
  This project is in collaboration with experimental work by professor L. Walldén and S.Å. Lindgren and A. Carlsson at our department. From a self-energy analysis of a quantum well hole state in an alkali overlayer on Cu(100), an expression for the electron-phonon induced lifetime broadening is derived. The electron wave function of quantum well states in the overlayer are quantized normal to the surface and of plane-wave type parallel to the surface. According to our model, the temperature dependent part of the contribution to the width of the observed Lorentzian shaped photo-emission line originates from phonon mediated electron scattering from inter-sub band scattering from nearby resonance states. This imply that the electrons couples predominantly to phonon modes polarized perpendicular to the surface, the so called organ-pipe like modes. Comparing the theoretically predicted temperature dependent lifetime broadening with experiment give information of the strength of the electron-phonon coupling strength in metal overlayers, the T-independent part of the broadening and the complex interplay of phonon energies, temperature and hole-state energy. Publications [38,40,41].
  We are planning to set up a calculation of the system Cs/Cu(111) as this system has been characterized experimentally by Wallden et al. in details both concerning the formation of quantum well states (QWS), vibrational properites and low temperature ARPES measurements are in progress giving information about the lifetime broadening. We will obtain the electronic and vibrational structure which will serve as an input to the investigation of the fundamental electron-phonon and electron-electron scattering responsible for the lifetime broadening. Collaboration with the local experimental group and the San Sebastian group.

• Lifetime of surface states and image states on metals - including electron-phonon and electron-electron interaction. A collaboration with the San Sebastian group; professor P.M. Echenique, professor E. Chulkov and PhD student A.E. Goienetxea. The aim is to compare the contributions from electron-phonon and electron-electron interaction to the experimentally observed lifetimes of surface states and surface image states on clean metal surfaces. We have investigated the surface state of Cu(111) and Ag(111) and compared with High Resolution PES data [47,50,53]

• Strong correlation in electron systems (2008-). DMFT studies of the phase diagram of Mott insulator. LDA+U and LDA+Gutzwiller invetsigations of bulk STO and LAO and the 2D electron gas in the interface of LAO/STO.

• Electron-phonon coupling in graphene.