General info > Workshop
Program for Workshop of "APIANS (Analysis for Polymeric Insulating materials using Advanced Numerical Simulation)"
Date: 14:00 - 17:00, June 1, 2014
Place: Toki Messe, Niigata City, Japan
Note: Lecturers' biographies are listed after the program in this web page.
14:00 - 14:10, Prof. Toshikatsu Tanaka, Waseda Univ.: Chairman's Introduction
14:10 - 14:40, Prof. Steven A. Boggs, Univ. Connecticut
- Title: The Application of Computational Methods to the Design of Dielectric Materials and Systems
- Resume: "Computational materials" spans a wide range of approaches to the application of computational techniques to the design of materials,
ranging from computational quantum mechanics to finite element analysis. This presentation will provide an overview of approaches relevant to the
design and development of dielectric materials, including:
1) The use of computational quantum mechanics to compute material properties such as dielectric constant, band gap, impurity states in the band gap,
intrinsic breakdown field, infrared spectra and, hopefully, engineering breakdown.
2) The use of molecular dynamics to compute polymer morphology, dielectric loss, etc.
The objective of the seminar will be to provide an indication of what is now possible, what is becoming possible, how these technologies are adding
value to dielectric materials, and why they will become indispensable in the future. The seminar is based on work of a US Office of Naval Research
sponsored "MultiUniversity Research Initiative" (MURI) 5-year project which involves the University of Connecticut, Columbia University,
The Pennsylvania State University, Rensselear Polytechnique, and The University of Akron and represents the work of 7 professors, their students and
PDF's who are involved in the research.
14:40 - 15:10, Dr. Mikael Unge, ABB
- Title: First Principle Simulations of Electronic Structure of Polymer Dielectrics
- Resume: To understand electron and hole transport in solid material requires to know its electronic properties, i.e. the density of states (DOS)
and the character of the states, i.e., whether they are spatially localized or delocalized. Localized states may act as traps, recombination centers or
hopping sites. Traps release carriers back to transport states via carrier hopping. Delocalized states contribute to band-like transport. The states closest
to the band edges are localized, states further away can be delocalized. This transition from localized to delocalized states determines the mobility edge,
above the mobility edge the mobility is expected to be high. A real polymer is never perfect; it contains a number of oxidative states, bonding defects and
molecular impurities. These imperfections yield electronic states that can appear in the band gap of the polymer, traps. Traps can be shallow, i.e. close to
the band edges, from these states the charge carrier easily can jump to a state in the band edge or another shallow state. Other traps can be deep, in these
states it is likely that the charge carrier remains and become immobile. All these properties related to the electronic structure of the polymer, including
its defects, affects the conductivity of the polymer.
Material simulation techniques can be applied to calculate the electronic structure e.g. DOS. Density Functional Theory (DFT) is a so called ab initio or
first principle theory where no parameters are needed. For geometries including more than 100 atoms linear scaling version of DFT needs to be applied. For
really large systems such as the amorphous phase of polyethylene, where approximately 2000 atoms needs to be considered, classical methods like Molecular
Dynamics (MD) have to be applied to find global minimum of the geometry.
In this presentation I will discuss how linear scaling DFT can be applied to calculate electronic structure properties of polymer dielectrics. The simulations
include different phases of the polymer (crystalline, amorphous and their interface) and defects and impurities. The presentation is based on our previously
published work [1, 2] and work to be submitted for publication.
- Related referenes:
[1] Unge, M., T. Christen, and C. Tornkvist. Electronic structure of polyethylene - Crystalline and amorphous phases of pure polyethylene and their
interfaces. in Electrical Insulation and Dielectric Phenomena (CEIDP), 2012 Annual Report Conference on. 2012. Montreal, Canada.
[2] Unge, M., T. Christen, and C. Tornkvist. Space charges and deep traps in polyethylene - abinitio simulations of chemical impurities and defects. in
International Conference on Solid Dielectrics (ICSD), 2013. 2013. Bologna, Italy.
15:10 - 15:40, Prof. Tatsuo Takada, Tokyo City Univ.
- Title: Determination of Charge-Trapping Sites in Saturated and Aromatic Polymers by Quantum Chemical Calculation
- Resume: We have studied the relationship between the experimental results of electric charge accumulation in polymeric insulation materials under a
high electric field and the trapping sites of positive and negative charges in the chemical structures of polymers using quantum chemical calculation. For
example, positive charges accumulated in low-density polyethylene (LDPE), whereas positive and negative charges accumulated in polyimide (Kapton?) and also in
ethylene-tetrafluoro-ethylene (ETFE) subjected to electron beam irradiation. To determine charge-trapping sites in chemical structures, a quantum chemical
calculation was carried out using Gaussian 09 software. The relationship between the energy band and the iso-surface of orbital electrons at various energy
levels was obtained. A three- dimensional (3D) electrostatic potential distribution map was obtained for positively and negatively charged polymers to determine
the relationship between a trapping site and the charge accumulation center in the 3D potential distribution map. Positive and negative charges in Kapton and
ETFE films are trapped in trapping sites in chemical structures and the positive charges in LDPE film are trapped in physical defects.
15:40 - 16:00, Break (20 minutes)
16:00 - 16:30, Dr. Severine Le Roy, Univ. Toulouse
- Title: Modelling Charge Transport and Storage in Polymeric Insulating Materials: Numerical Analysis, Optimization and Validation
- Resume: Challenges in the field of solid insulating materials are linked to the development of more compact, reliable and eco-friendly systems for
conversion and transport of electric energy. Models describing the generation and transport of charges in solid organic dielectrics would be extremely useful
in order to predict the material behaviour, and to answer to the main industrial issues. A homemade fluid model of charge transport and storage is presented and
illustrated by examples of simulation results using different stressing conditions. Challenges and limitations of the numerical schemes used in such fluid (also
called drift-diffusion) models are illustrated and discussed. Finally, a special attention is put on optimization tools, often used to find the best set of
parameters to feed the drift-diffusion models. Such tools are powerful, but their development is not so trivial and errors can arise either when parameterizing
the optimization tool or when feeding this tool with experimental results.
16:30 - 17:00, Assoc. Prof. David Cubero, Univ. Sevilla
- Title: Numerical Simulation Methods to Model Electron Trapping and Transport in Polyethylene at the Molecular Level
- Resume: After many years of research, a deep understanding of the behavior of charge carriers in polyethylene, the most common polymeric insulator,
still remains elusive. Here we will review the main molecular simulation techniques which have been used, and are still been used, to investigate the
mechanisms of electron trapping and transport in polyethylene, highlighting the difficulties and limitations of each theoretical technique.
Lecturers' biographies
Prof. Steven A. Boggs, Univ. Connecticut
Steven Boggs was graduated with a B.A. in physics from Reed College and received his Ph.D. and MBA degrees from the University of Toronto in 1972 and 1987, respectively.
He spent 12 years with the Research Division of Ontario Hydro and 6 years as Director of Engineering and Research for Underground Systems, Inc. Steve recently retired
from his position as Director of the Electrical Insulation Research Center of the University of Connecticut and Research Professor of Materials Science, Physics, and
Electrical Engineering, although he is still working on a number of projects at the University. Until recently, he was also an Adjunct Professor of Electrical
Engineering at the University of Toronto. He has published widely in the areas of partial discharge measurement, high frequency phenomena in power apparatus, high field
phenomena in solid dielectrics, capacitor technology, and SF
6 insulated systems. He was elected a Fellow of the IEEE for his contributions to the field of
SF
6 insulated systems and received the 2010 IEEE Thomas W. Dakin "Distinguished Technical Contributions" award. Presently, Steve spends most of his time
doing computational research for a range of companies in the US and Asia through his company, Nonlinear Systems, Inc.
Dr. Mikael Unge, ABB
Mikael Unge was born in Kumla, Sweden in 1977. He received the M.Sc. degree in applied physics and electrical engineering in 2001 and the Ph.D. degree in computational
physics in 2006 both from Linkoping University, Sweden. During 2007-2008 he was a Postdoc at the Center for Atomic-Scale Materials Design at the Technical University of
Denmark, Copenhagen, Denmark. Since 2008 he works as a researcher at ABB Corporate Research in Vasteras, Sweden. His research interest includes influence of molecular
properties on the dielectric performances of insulating materials.
Prof. Tatsuo Takada, Tokyo City Univ.
Tatsuo Takada was born in August 8, 1939, received his B.E. degree in electrical engineering from Musashi Institute of Technology, Japan, in 1963, his M.E. degree from
Tohoku University, Japan, in 1966, and his doctoral degree from Tohoku University in 1975. Appointed a lecturer at Musashi Institute of Technology in 1967, he became an
associate professor at the same university in 1974, a professor in 1987 and emeritus professor of Tokyo City University (before Musashi Institute of Technology) in 2006.
He was a visiting scientist at MIT (USA) from 1981 to 1983 and he is a consulting professor of Xian Jiaotong University, China. He has undertaken several research projects
on the development of acoustic and optical advanced methods for measuring electric charge distribution in dielectrics. For example, in order to investigate the space charge
effect in solid dielectric material, the dynamic surface charge distribution on solid dielectrics and the electric field vector distribution in liquid insulating materials.
He received excellent paper awards from the IEE of Japan in 1974, 1981 and 1990 and the progress award from the IEE of Japan in 1996, and also the Whitehead Memorial
award from the IEEE, CEIS in 1999. He is a Fellow member of IEEE.
Dr. Severine Le Roy, Univ. Toulouse
Severine Le Roy graduated in 2001 in molecular and structural physical chemistry at the Joseph Fourier University, Grenoble, France. Then she joined the Electrical Engineering
Laboratory in Toulouse (LGET) and obtained her Ph.D. degree in electrical engineering in 2004 from Paul Sabatier University. She entered the CNRS (National Centre of
Scientific Research) in 2006. She is now dealing with modelling activities in relation with charge transport and ageing, for various domains of applications like electrical
engineering, spatial environment and thin films. She is also concerned in the relationship between experiments and simulations.
Assoc. Prof. David Cubero, Univ. Sevilla
David Cubero was born in Spain in 1971. He received his Ph.D degree in physics from University of Seville in 1996. He was a post-doctorate researcher at Imperial College London,
UK, from 2001 to 2004. He is now an associate professor at the University of Seville (Spain) specializing in the area of nonequilibrium statistical physics, including
transport theory and resonant phenomema. He has published more than 30 papers in leading journals on a wide range of topics in Stastistical Mechanics, including granular flows,
Brownian motors, relativistic systems, and electronic transport.