The document describes a research group's work on simulating semiconductor devices using electromagnetic and particle-based simulation methods. It aims to accurately capture radiated electromagnetic fields from high-frequency nanostructure devices. The group is developing a simulator that couples Maxwell's equations and the Boltzmann transport equation to model carrier transport and electromagnetic wave propagation. It initializes simulations using empirical pseudopotential bandstructure models and calculates particle motion through free flight and scattering.
The document discusses reduced order modeling for transient analysis of carbon nanotube interconnects. It proposes using a half-T ladder network model and rational functions to develop a macromodel of a CNT interconnect from its per unit length parameters. The macromodel represents the interconnect admittance matrix using poles and residues, allowing for efficient transient analysis. Numerical results show the macromodel accurately captures the behavior of a CNT interconnect under various transient signals. An experimental setup is also developed to characterize CNT interconnects.
Electronic Structures and UV/Visible Absorption Spectra of Organic CompundsFa-Gung Fan
Fa-Gung Fan presented calculations of the electronic structures and UV/visible absorption spectra of several organic compounds of interest for solar cell materials. The compounds studied included coumarin derivative dyes, flavone, and donor-acceptor systems. Ab initio and semi-empirical methods were used to calculate molecular orbitals, energy gaps, and absorption spectra. The results were in good agreement with previous studies and can help optimize materials selection for solar cells.
This document summarizes a new algorithm called MewDC-NMF for unsupervised unmixing of hyperspectral images. MewDC-NMF stands for Minimum endmember-wise Distance Constrained Nonnegative Matrix Factorization. It simultaneously extracts endmembers and estimates abundance fractions without requiring pure pixels. This is accomplished by imposing a distance constraint between endmembers to make their spectra more compact during optimization. Experiments on synthetic and real AVIRIS data show MewDC-NMF outperforms other constrained NMF methods in extracting more accurate endmembers and estimating abundances.
This document describes a study analyzing the magnetization of a ferrite bonded magnet used in an inner-rotor brushless DC motor without a rotor core.
The study uses finite element analysis to determine the non-uniform magnetization distribution of the bonded magnet, accounting for the anisotropic magnetization that occurs during its manufacturing process. With the determined magnetization distribution, the performance of the BLDC motor is analyzed and compared to experimental results.
The analysis finds that accounting for the non-uniform, anisotropic magnetization distribution of the bonded magnet, rather than assuming a uniform radial distribution, provides a more accurate prediction of the motor's back EMF waveform, speed-torque characteristics, and effects of magnet thickness variations
Full-Band/Full-Wave Simulations of InGaAs-based Pseudomorphic HEMTsayubimoak
The document describes the Nanostructures Research Group at the Center for Solid State Electronics Research. The group conducts research on nanostructures including developing hybrid computational methods to model bandstructure and phonon spectra. It studies scattering mechanisms in devices and uses Poisson solvers. The group analyzes strained InGaAs materials and investigates high-frequency transistors down to 10 nm gate lengths. It also models electromagnetic wave propagation using Maxwell's equations and the Yee cell method with perfectly matched layer boundary conditions.
Localization of Low Complexity Communication Devices via Mutual Inductive Cou...Simone Baffelli
The document presents a method for localizing small-scale communication devices using mutual inductive coupling. It proposes measuring the coupling coefficient between devices to obtain location information. An algorithm is developed to estimate the 5D parameters (3D position and 2D orientation) of agents by minimizing the difference between measured and predicted coupling coefficients. Simulations show the method can localize agents with an error of less than 1 meter, even with noise, and is robust to reduced measurement precision. Tracking of moving agents is also demonstrated.
Prediction of Pcb Radiated Emissions (Emc Symposium Zurich 1998)Piero Belforte
The paper shows the experimental validation of predictive results of radiated emissions of a multilayer pcb. The radiated field is calculated from simulated results of pcb signals obtained from DWN analysis of interconnects.
Integral Equation Formulation of Electromagnetic Scattering from Small ParticlesHo Yin Tam
1) The document discusses various methods for modeling electromagnetic scattering from small particles, including integral equation formulations, the T-matrix method, and finite-difference time-domain (FDTD) simulations.
2) It finds that the T-matrix method most accurately calculates internal fields, while FDTD has significant errors near particle surfaces.
3) An analytic approximation (AA) approach is presented that separates shape and frequency dependencies for simple calculations of internal fields in small particles.
The document discusses reduced order modeling for transient analysis of carbon nanotube interconnects. It proposes using a half-T ladder network model and rational functions to develop a macromodel of a CNT interconnect from its per unit length parameters. The macromodel represents the interconnect admittance matrix using poles and residues, allowing for efficient transient analysis. Numerical results show the macromodel accurately captures the behavior of a CNT interconnect under various transient signals. An experimental setup is also developed to characterize CNT interconnects.
Electronic Structures and UV/Visible Absorption Spectra of Organic CompundsFa-Gung Fan
Fa-Gung Fan presented calculations of the electronic structures and UV/visible absorption spectra of several organic compounds of interest for solar cell materials. The compounds studied included coumarin derivative dyes, flavone, and donor-acceptor systems. Ab initio and semi-empirical methods were used to calculate molecular orbitals, energy gaps, and absorption spectra. The results were in good agreement with previous studies and can help optimize materials selection for solar cells.
This document summarizes a new algorithm called MewDC-NMF for unsupervised unmixing of hyperspectral images. MewDC-NMF stands for Minimum endmember-wise Distance Constrained Nonnegative Matrix Factorization. It simultaneously extracts endmembers and estimates abundance fractions without requiring pure pixels. This is accomplished by imposing a distance constraint between endmembers to make their spectra more compact during optimization. Experiments on synthetic and real AVIRIS data show MewDC-NMF outperforms other constrained NMF methods in extracting more accurate endmembers and estimating abundances.
This document describes a study analyzing the magnetization of a ferrite bonded magnet used in an inner-rotor brushless DC motor without a rotor core.
The study uses finite element analysis to determine the non-uniform magnetization distribution of the bonded magnet, accounting for the anisotropic magnetization that occurs during its manufacturing process. With the determined magnetization distribution, the performance of the BLDC motor is analyzed and compared to experimental results.
The analysis finds that accounting for the non-uniform, anisotropic magnetization distribution of the bonded magnet, rather than assuming a uniform radial distribution, provides a more accurate prediction of the motor's back EMF waveform, speed-torque characteristics, and effects of magnet thickness variations
Full-Band/Full-Wave Simulations of InGaAs-based Pseudomorphic HEMTsayubimoak
The document describes the Nanostructures Research Group at the Center for Solid State Electronics Research. The group conducts research on nanostructures including developing hybrid computational methods to model bandstructure and phonon spectra. It studies scattering mechanisms in devices and uses Poisson solvers. The group analyzes strained InGaAs materials and investigates high-frequency transistors down to 10 nm gate lengths. It also models electromagnetic wave propagation using Maxwell's equations and the Yee cell method with perfectly matched layer boundary conditions.
Localization of Low Complexity Communication Devices via Mutual Inductive Cou...Simone Baffelli
The document presents a method for localizing small-scale communication devices using mutual inductive coupling. It proposes measuring the coupling coefficient between devices to obtain location information. An algorithm is developed to estimate the 5D parameters (3D position and 2D orientation) of agents by minimizing the difference between measured and predicted coupling coefficients. Simulations show the method can localize agents with an error of less than 1 meter, even with noise, and is robust to reduced measurement precision. Tracking of moving agents is also demonstrated.
Prediction of Pcb Radiated Emissions (Emc Symposium Zurich 1998)Piero Belforte
The paper shows the experimental validation of predictive results of radiated emissions of a multilayer pcb. The radiated field is calculated from simulated results of pcb signals obtained from DWN analysis of interconnects.
Integral Equation Formulation of Electromagnetic Scattering from Small ParticlesHo Yin Tam
1) The document discusses various methods for modeling electromagnetic scattering from small particles, including integral equation formulations, the T-matrix method, and finite-difference time-domain (FDTD) simulations.
2) It finds that the T-matrix method most accurately calculates internal fields, while FDTD has significant errors near particle surfaces.
3) An analytic approximation (AA) approach is presented that separates shape and frequency dependencies for simple calculations of internal fields in small particles.
The document analyzes microstrip transmission lines using a quasi-static approach. It presents numerically efficient and accurate formulas to analyze microstrip line structures. The analysis derives formulas for characteristic impedance of microstrip lines based on variables like the normalized strip width, effective permittivity, height of the substrate, and thickness of the microstrip line. It also defines the structure of a microstrip line and formulates the quasi-static analysis by introducing the concept of an effective relative dielectric constant to account for the microstrip being surrounded by different dielectrics like air and the substrate material.
The document presents a three-level mathematical model of a well-stirred catalytic reactor with bidispersed catalysts. The model describes (1) the completely stirred fluid phase on the first level, (2) diffusion in the macropores on the second level, and (3) diffusion and reaction in the micropores on the third level. The model equations are solved using multilevel collocation to investigate transient phenomena in the reactor via computer simulation.
This document numerically analyzes the wave function of atoms under the combined effects of an optical lattice trapping potential and a harmonic oscillator potential, as used in Bose-Einstein condensation experiments. It employs the Crank-Nicolson scheme to solve the Gross-Pitaevskii equation. The results show that the wave function distribution responds to parameters like the trapping frequencies ratio, optical lattice intensity, chemical potential, and energy. Careful adjustment of the time step and grid spacing is needed to satisfy conservation of norms and energy as required by the physical system. Distributions of the overlapping potentials for different q-factors are presented.
Malcolm Jardine completed a summer placement project to set up an optical magnetometer using a cesium gas cell. Tri-axial Helmholtz coils were constructed and modeled in MATLAB to create a controlled magnetic field for testing the magnetometer. The magnetometer was able to correctly measure magnetic fields with an initial sensitivity of 0.3μT. MATLAB was also used to develop programs for modeling the magnetic fields of the coils and performing linear regression analysis of experimental data.
The document discusses the Mitsubishi Chemical Center for Advanced Materials (MC-CAM), a research partnership between Mitsubishi Chemical and UCSB focused on new materials. It also discusses the Complex Fluids Design Consortium (CFDC), an academic-industrial partnership aimed at developing computational tools for designing soft materials. The author proposes using field-based simulations rather than particle-based simulations to model polymer fluids at relevant scales, and describes how statistical field theories can be constructed and simulated at either a mean-field or full stochastic level.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
The document presents a mathematical model for the static I-V characteristics of optically controlled GaAs MESFETs. The model characterizes photo-induced voltages, including internal and external photovoltages, as well as photoconductive current in the channel. It also considers the effects of deep level traps in the semi-insulating GaAs substrate, including the phenomenon of backgating, on the I-V characteristics. The model is developed analytically and expressions are derived for the I-V characteristics in both the linear and saturation regions of the MESFET under dark and illuminated conditions. Small-signal parameters of the GaAs MESFET are also derived based on the static I-V model under optical control conditions
The document describes an electronics lab course that focuses on antenna design and implementation of digital communication systems using MATLAB/Simulink. The course covers topics like using a slotted line to determine unknown frequency and reflection coefficients, investigating yagi antennas by examining driven elements, reflectors and directors, and studying the effects of conductor thickness on bandwidth. It also includes implementing digital modulation and coding techniques like PCM, PSK and FSK using MATLAB. Students use antenna hardware and software to study properties of dipole antennas and parasitic elements in yagi antenna systems.
The document describes an electronics lab course that focuses on antenna design and implementation of digital communication systems using MATLAB/Simulink. The course covers topics like using a slotted line to determine unknown frequency and reflection coefficients, investigating yagi antennas by examining driven elements and parasitic directors and reflectors, and implementing modulation/demodulation techniques like PCM, PPM, and various digital coding formats in software simulations. Students will explore how antenna performance is affected by parameters like element thickness and stacking/baying configurations. The course aims to help students understand fundamental antenna properties and simulate key communication systems.
General Theory of electronic configuration of atomsIOSR Journals
The “General Theory of electronic configuration of atoms” is an original study introduced by the author in chemistry in 2004. In this paper, the author developed a new method to write the electronic configuration for any atom, regardless of whether it actually exists or not in nature. This new method is based on Quantum theory and on three new and original formulae introduced and developed by the author. This method can be used to gather information about any atom’s properties: its period, its group, its peripheral number of electrons and its theoretical electronic peripheral configuration. The main advantage of this method is that one can immediately knows the information about an atom, by a simple hand calculation without the need of software. Even if the atomic number is huge (as Z=123453). This method can be used in general chemistry courses and it is an extremely efficient method used for teaching and in the exam.
So any atomic number can be developed and we can find its electronic configuration regardless of whether it actually exists or not in nature.
-The traditional method of writing an electronic configuration is like this
⏞ ⏞ ⏞ ⏞ ⏞ ⏞ Until finding the peripheral electronic configuration.
So the new method developed in this paper is mainly works on the peripheral electronic configuration without passing through the traditional method. It gives us directly the peripheral electronic configuration, for example ⏞ .
In this way we have eliminated a very long process of calculation. This is a big advantage for the proposed method ahead the traditional one.
The main goal of introducing this paper is to reduce the calculation of obtaining the main information about an atom for example its period, group, number of electrons in the peripheral configuration and finding its peripheral electronic configuration as fast as possible even if the atom doesn’t exist in reality. This paper doesn’t explain the relativistic effects, because it is not the main goal of the proposed theory. We can still obtain the information about any atom without considering the relativistic effects.
Theoretical Investigation on CuxV2-xO5 where x=0, 0.5 Using Density Functiona...IRJET Journal
This document presents a theoretical investigation of V2O5 and Cu0.5V1.5O5 using density functional theory. The calculations were performed using the Vienna Ab-initio Simulation Package. For V2O5, the lattice parameters were underestimated by 1-1.5% compared to experimental values. The bulk modulus was overestimated. V2O5 had a direct bandgap of 2.28 eV and a cohesive energy of 8.67 eV. For Cu0.5V1.5O5, there was no bandgap between the valence and conduction bands, making it conductive. Its cohesive energy was lower than V2O5, indicating V2O5 is more stable.
This document provides an introduction to the Vienna Ab Initio Simulation Package (VASP) software for performing density functional theory (DFT) calculations. It describes key aspects of DFT and the plane wave basis used in VASP, including exchange-correlation functionals, pseudopotentials, and common input/output files like INCAR, POSCAR, POTCAR and KPOINTS. Online resources for learning more about VASP and DFT are also listed.
An R-matrix approach for plasma modelling and the interpretation of astrophys...AstroAtom
This document provides a 3-sentence summary of an expert presentation on plasma modeling and interpretation using an R-matrix approach:
The presentation discussed comprehensive plasma modeling capabilities using R-matrix calculations of electron-impact ionization, excitation, and photoionization of mid-Z elements, which have been parallelized to efficiently utilize modern high performance computing architectures. Scripted R-matrix calculations along iso-nuclear sequences automate the calculation of effective collision strengths. Examples were given of parallel calculations of electron-impact excitation of Fe III and photoionization of Kr II and Xe II using the Dirac Atomic R-matrix Codes that agree well with experimental results.
This document provides a report on a maglev train submitted for a Bachelor of Technology degree. It includes an abstract, introduction on maglev train concepts, and sections on the track, propulsion, inductrack technology, simulation, previous work done, levitation experiments, track fabrication, advantages, and references. The report describes the design and testing of a small-scale maglev train model based on inductrack technology with the goal of achieving levitation at lower speeds. Previous work by Paul Friend is discussed, where he constructed a wheel-track test platform and optimization program to calculate train parameters.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
This document compares the electron transport properties of zincblende and wurtzite crystal structures of indium nitride (InN) at high electric fields. Monte Carlo simulations were performed using a three-valley model. Results show zincblende InN has a higher electron drift velocity of 3.6×105 m/s at a breakdown field of 1.71×107 V/m, compared to 2.8×105 m/s for wurtzite InN at 3.34×107 V/m. Zincblende InN also has higher electron mobility of 0.183 m2/Vs versus 0.075 m2/Vs for wurtzite InN at
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Benchmark Calculations of Atomic Data for Modelling ApplicationsAstroAtom
This document summarizes benchmark calculations of atomic data for modeling applications. It discusses numerical methods like close-coupling and distorted-wave approaches for calculating atomic collision data. It provides selected results on energy levels, oscillator strengths, and electron-impact excitation cross sections. It also discusses applications to modeling neon discharges and takes a closer look at ionization calculations and examples. The document concludes by discussing the production and assessment of atomic data and outlines challenges in obtaining reliable data from both experiments and calculations.
Analysis and Design of Lead Salt PbSe/PbSrSe Single Quantum Well In the Infra...IJASCSE
There is a considerable interest in studying the energy spectrum changes due to the non parabolic energy band structure in nano structures and nano material semiconductors. Most material systems have parabolic band structures at the band edge, however away from the band edge the bands are strongly non parabolic. Other material systems are strongly parabolic at the band edge such as IV-VI lead salt semiconductors. A theoretical model was developed to conduct this study on PbSe/Pb 0.934 Sr0.066 Se nanostructure system in the infrared region. Moreover, we studied the effects of four temperatures on the analysis and design of this system. It will be shown that the total losses for the system are higher than the modal gain values for lasing to occur and multiple quantum well structures are a better design choice.
State of charge estimation of lithium-ion batteries using fractional order sl...ISA Interchange
This paper presents a state of charge (SOC) estimation method based on fractional order sliding mode observer (SMO) for lithium-ion batteries. A fractional order RC equivalent circuit model (FORCECM) is firstly constructed to describe the charging and discharging dynamic characteristics of the battery. Then, based on the differential equations of the FORCECM, fractional order SMOs for SOC, polarization voltage and terminal voltage estimation are designed. After that, convergence of the proposed observers is analyzed by Lyapunov’s stability theory method. The framework of the designed observer system is simple and easy to implement. The SMOs can overcome the uncertainties of parameters, modeling and measurement errors, and present good robustness. Simulation results show that the presented estima- tion method is effective, and the designed observers have good performance.
More Related Content
Similar to Coupling Maxwell\'s Equations to Particle-Based Simulators
The document analyzes microstrip transmission lines using a quasi-static approach. It presents numerically efficient and accurate formulas to analyze microstrip line structures. The analysis derives formulas for characteristic impedance of microstrip lines based on variables like the normalized strip width, effective permittivity, height of the substrate, and thickness of the microstrip line. It also defines the structure of a microstrip line and formulates the quasi-static analysis by introducing the concept of an effective relative dielectric constant to account for the microstrip being surrounded by different dielectrics like air and the substrate material.
The document presents a three-level mathematical model of a well-stirred catalytic reactor with bidispersed catalysts. The model describes (1) the completely stirred fluid phase on the first level, (2) diffusion in the macropores on the second level, and (3) diffusion and reaction in the micropores on the third level. The model equations are solved using multilevel collocation to investigate transient phenomena in the reactor via computer simulation.
This document numerically analyzes the wave function of atoms under the combined effects of an optical lattice trapping potential and a harmonic oscillator potential, as used in Bose-Einstein condensation experiments. It employs the Crank-Nicolson scheme to solve the Gross-Pitaevskii equation. The results show that the wave function distribution responds to parameters like the trapping frequencies ratio, optical lattice intensity, chemical potential, and energy. Careful adjustment of the time step and grid spacing is needed to satisfy conservation of norms and energy as required by the physical system. Distributions of the overlapping potentials for different q-factors are presented.
Malcolm Jardine completed a summer placement project to set up an optical magnetometer using a cesium gas cell. Tri-axial Helmholtz coils were constructed and modeled in MATLAB to create a controlled magnetic field for testing the magnetometer. The magnetometer was able to correctly measure magnetic fields with an initial sensitivity of 0.3μT. MATLAB was also used to develop programs for modeling the magnetic fields of the coils and performing linear regression analysis of experimental data.
The document discusses the Mitsubishi Chemical Center for Advanced Materials (MC-CAM), a research partnership between Mitsubishi Chemical and UCSB focused on new materials. It also discusses the Complex Fluids Design Consortium (CFDC), an academic-industrial partnership aimed at developing computational tools for designing soft materials. The author proposes using field-based simulations rather than particle-based simulations to model polymer fluids at relevant scales, and describes how statistical field theories can be constructed and simulated at either a mean-field or full stochastic level.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
The document presents a mathematical model for the static I-V characteristics of optically controlled GaAs MESFETs. The model characterizes photo-induced voltages, including internal and external photovoltages, as well as photoconductive current in the channel. It also considers the effects of deep level traps in the semi-insulating GaAs substrate, including the phenomenon of backgating, on the I-V characteristics. The model is developed analytically and expressions are derived for the I-V characteristics in both the linear and saturation regions of the MESFET under dark and illuminated conditions. Small-signal parameters of the GaAs MESFET are also derived based on the static I-V model under optical control conditions
The document describes an electronics lab course that focuses on antenna design and implementation of digital communication systems using MATLAB/Simulink. The course covers topics like using a slotted line to determine unknown frequency and reflection coefficients, investigating yagi antennas by examining driven elements, reflectors and directors, and studying the effects of conductor thickness on bandwidth. It also includes implementing digital modulation and coding techniques like PCM, PSK and FSK using MATLAB. Students use antenna hardware and software to study properties of dipole antennas and parasitic elements in yagi antenna systems.
The document describes an electronics lab course that focuses on antenna design and implementation of digital communication systems using MATLAB/Simulink. The course covers topics like using a slotted line to determine unknown frequency and reflection coefficients, investigating yagi antennas by examining driven elements and parasitic directors and reflectors, and implementing modulation/demodulation techniques like PCM, PPM, and various digital coding formats in software simulations. Students will explore how antenna performance is affected by parameters like element thickness and stacking/baying configurations. The course aims to help students understand fundamental antenna properties and simulate key communication systems.
General Theory of electronic configuration of atomsIOSR Journals
The “General Theory of electronic configuration of atoms” is an original study introduced by the author in chemistry in 2004. In this paper, the author developed a new method to write the electronic configuration for any atom, regardless of whether it actually exists or not in nature. This new method is based on Quantum theory and on three new and original formulae introduced and developed by the author. This method can be used to gather information about any atom’s properties: its period, its group, its peripheral number of electrons and its theoretical electronic peripheral configuration. The main advantage of this method is that one can immediately knows the information about an atom, by a simple hand calculation without the need of software. Even if the atomic number is huge (as Z=123453). This method can be used in general chemistry courses and it is an extremely efficient method used for teaching and in the exam.
So any atomic number can be developed and we can find its electronic configuration regardless of whether it actually exists or not in nature.
-The traditional method of writing an electronic configuration is like this
⏞ ⏞ ⏞ ⏞ ⏞ ⏞ Until finding the peripheral electronic configuration.
So the new method developed in this paper is mainly works on the peripheral electronic configuration without passing through the traditional method. It gives us directly the peripheral electronic configuration, for example ⏞ .
In this way we have eliminated a very long process of calculation. This is a big advantage for the proposed method ahead the traditional one.
The main goal of introducing this paper is to reduce the calculation of obtaining the main information about an atom for example its period, group, number of electrons in the peripheral configuration and finding its peripheral electronic configuration as fast as possible even if the atom doesn’t exist in reality. This paper doesn’t explain the relativistic effects, because it is not the main goal of the proposed theory. We can still obtain the information about any atom without considering the relativistic effects.
Theoretical Investigation on CuxV2-xO5 where x=0, 0.5 Using Density Functiona...IRJET Journal
This document presents a theoretical investigation of V2O5 and Cu0.5V1.5O5 using density functional theory. The calculations were performed using the Vienna Ab-initio Simulation Package. For V2O5, the lattice parameters were underestimated by 1-1.5% compared to experimental values. The bulk modulus was overestimated. V2O5 had a direct bandgap of 2.28 eV and a cohesive energy of 8.67 eV. For Cu0.5V1.5O5, there was no bandgap between the valence and conduction bands, making it conductive. Its cohesive energy was lower than V2O5, indicating V2O5 is more stable.
This document provides an introduction to the Vienna Ab Initio Simulation Package (VASP) software for performing density functional theory (DFT) calculations. It describes key aspects of DFT and the plane wave basis used in VASP, including exchange-correlation functionals, pseudopotentials, and common input/output files like INCAR, POSCAR, POTCAR and KPOINTS. Online resources for learning more about VASP and DFT are also listed.
An R-matrix approach for plasma modelling and the interpretation of astrophys...AstroAtom
This document provides a 3-sentence summary of an expert presentation on plasma modeling and interpretation using an R-matrix approach:
The presentation discussed comprehensive plasma modeling capabilities using R-matrix calculations of electron-impact ionization, excitation, and photoionization of mid-Z elements, which have been parallelized to efficiently utilize modern high performance computing architectures. Scripted R-matrix calculations along iso-nuclear sequences automate the calculation of effective collision strengths. Examples were given of parallel calculations of electron-impact excitation of Fe III and photoionization of Kr II and Xe II using the Dirac Atomic R-matrix Codes that agree well with experimental results.
This document provides a report on a maglev train submitted for a Bachelor of Technology degree. It includes an abstract, introduction on maglev train concepts, and sections on the track, propulsion, inductrack technology, simulation, previous work done, levitation experiments, track fabrication, advantages, and references. The report describes the design and testing of a small-scale maglev train model based on inductrack technology with the goal of achieving levitation at lower speeds. Previous work by Paul Friend is discussed, where he constructed a wheel-track test platform and optimization program to calculate train parameters.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
This document compares the electron transport properties of zincblende and wurtzite crystal structures of indium nitride (InN) at high electric fields. Monte Carlo simulations were performed using a three-valley model. Results show zincblende InN has a higher electron drift velocity of 3.6×105 m/s at a breakdown field of 1.71×107 V/m, compared to 2.8×105 m/s for wurtzite InN at 3.34×107 V/m. Zincblende InN also has higher electron mobility of 0.183 m2/Vs versus 0.075 m2/Vs for wurtzite InN at
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Benchmark Calculations of Atomic Data for Modelling ApplicationsAstroAtom
This document summarizes benchmark calculations of atomic data for modeling applications. It discusses numerical methods like close-coupling and distorted-wave approaches for calculating atomic collision data. It provides selected results on energy levels, oscillator strengths, and electron-impact excitation cross sections. It also discusses applications to modeling neon discharges and takes a closer look at ionization calculations and examples. The document concludes by discussing the production and assessment of atomic data and outlines challenges in obtaining reliable data from both experiments and calculations.
Analysis and Design of Lead Salt PbSe/PbSrSe Single Quantum Well In the Infra...IJASCSE
There is a considerable interest in studying the energy spectrum changes due to the non parabolic energy band structure in nano structures and nano material semiconductors. Most material systems have parabolic band structures at the band edge, however away from the band edge the bands are strongly non parabolic. Other material systems are strongly parabolic at the band edge such as IV-VI lead salt semiconductors. A theoretical model was developed to conduct this study on PbSe/Pb 0.934 Sr0.066 Se nanostructure system in the infrared region. Moreover, we studied the effects of four temperatures on the analysis and design of this system. It will be shown that the total losses for the system are higher than the modal gain values for lasing to occur and multiple quantum well structures are a better design choice.
State of charge estimation of lithium-ion batteries using fractional order sl...ISA Interchange
This paper presents a state of charge (SOC) estimation method based on fractional order sliding mode observer (SMO) for lithium-ion batteries. A fractional order RC equivalent circuit model (FORCECM) is firstly constructed to describe the charging and discharging dynamic characteristics of the battery. Then, based on the differential equations of the FORCECM, fractional order SMOs for SOC, polarization voltage and terminal voltage estimation are designed. After that, convergence of the proposed observers is analyzed by Lyapunov’s stability theory method. The framework of the designed observer system is simple and easy to implement. The SMOs can overcome the uncertainties of parameters, modeling and measurement errors, and present good robustness. Simulation results show that the presented estima- tion method is effective, and the designed observers have good performance.
Similar to Coupling Maxwell\'s Equations to Particle-Based Simulators (20)
2. • Introduction / Motivation
• Full Band Simulator
• Finite-Difference Time Domain Method
(FDTD) / Maxwell Solver
• Coupling of Maxwell/Monte Carlo methods
• Simulation results / Conclusions
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
3. Traditional methods of simulating semiconductor devices involve a
solution of Poisson’s equation on a discrete mesh. However, the
static field distribution that results is unable to fully account for the
time-varying nature of the total electromagnetic environment
that exist within and surrounding the device.
• As operating frequencies increase, must treat signals as
electromagnetic waves propagating along transmission
lines in devices.
• Must take into account absorption /emission of EM
energy throughout system.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
4. Development of devices operating in this new high-frequency
regime is occuring on two separate ends of a gap.
Terahertz Gap
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
5. Current research motivated by a desire to accurately simulate and
capture radiated EM field patterns emanating from ultrafast, high
-frequency devices
Experimental measurements of high-field transport in GaAs and InP
under extreme non-equilibrium conditions have been reported by
Leitenstorfer et. al.1
Recent numerical experiments of transient responses in GaAs and
InP by Wigger et. al.2 have provided further motivation for this work
1A. Leitenstorfer, S. Hunsche, J. Shah, M.C. Nuss, and
W.H. Knox: Phys. Rev. Lett. 82 5140 (1999).
2S. Wigger, M. Saraniti, S. Goodnick, A. Leitenstorfer:
J. Comp. Elec. 1:475-480 (2002)
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
6. • Introduction / Motivation
• Particle-Based Simulator
• Finite-Difference Time Domain Method
(FDTD) / Maxwell Solver
• Coupling of Maxwell/Monte Carlo Methods
• Simulation results / Conclusions
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
7. Use a semiclassical description of carrier transport via stochastic solution of
the Boltzmann Transport Equation (BTE),
Boltzmann Transport Equation:
drift diffusion
where,
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
8. initialization
Flowchart of Simulator:
calculate charge
Poisson solver
free flight
particle dynamics
NO
end simulation time ?
YES
calculate averages
end
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
9. initialization
parabolic dispersion: fullband dispersion:
6
4
energy [eV]
2
0
non-parabolic dispersion: -2
-4
-6
L X U,K
L L
wave vector
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
10. Initialization: initialization
Empirical Pseudopotential Method
density of states [10 cm eV ] 5
density of states [10 cm eV ]
-1
-1
7 InP GaAs
-3
-3
6 4
22
5
22
3
4
3 2
2
1
1
L L
L L
wave vector
wave vector
X X
U,K U,K
L L
-10 -5 0 5 10 -10 -5 0 5 10
energy [eV] energy [eV]
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
11. Initialization: initialization
Phonon Dispersion
Valence Shell Method
0 .0 5 0 .0 4
LO
InP LO GaAs
0 .0 4
TO 0 .0 3 TO
energy [eV]
energy [eV]
0 .0 3
0 .0 2
0 .0 2
LA LA
0 .0 1
0 .0 1 LA LA
TA TA TA
TA
0 L L 0
L X U,K
L L
L X U,K
wave vector wave vector
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
12. Free Flight: Drift
free flight
Newton’s Equations of motion:
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
13. Ensemble Monte Carlo vs.“Cellular Monte Carlo”
The Ensemble Monte Carlo The Cellular Monte Carlo method
method tabulates the scattering computes and tabulates the
rate integrated over the entire scattering rates from an initial
momentum space. The final state momentum state to all possible
is then obtained by inverting the final states, which satisfy the
energy-momentum dispersion appropriate conservation laws.
relation, which is also tabulated
for full band.
choose scattering
choose new k
new energy
computationally fast
find new k with high memory requirements
dispersion relation
Scattering Mechanisms:
computationally slow polar scattering
low memory requirements deformation potential scattering
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
impact ionization
14. Hybrid EMC/CMC
Idea:
use MC scattering in regions of band structure where scattering is low.
Nearly as fast as CMC.
Reduces memory usage.
Hybrid/MC performance ratio
time per iter. [sec/5000 e ]
-
6
4
energ y [eV]
2
0
-2
-4 EMC
-6 CMC
X U,K
L L
L
wave vector
field [V/m]
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
15. • Introduction / Motivation
• Full Band Simulator
• Finite-Difference Time Domain Method
(FDTD) / Maxwell Solver
• Coupling of Maxwell/Monte Carlo Methods
• Simulation results / Conclusions
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
16. “Finite-Difference Time-Domain”
• First introduced by K. S. Yee in 1966.
• Method remained relatively unused for ~10 yrs.
Inadequate processing power.
Method lacked proper boundary conditions.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
17. Curl form of necessary Maxwell
equations are:
Constitutive Relationships
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
18. By applying the curl operator and equating the vector components
of the previous (2) equations, we arrive at the following set of (6)
scalar equations:
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
19. Now, using a centered-difference scheme, each expression can
be rewritten in appropriate finite-difference form shown here:
Note that E & H Fields are offset
Magnetic Field Update Equation from each other.
Electric Field Update Equation
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
20. • Scheme is often referred to as a “Leapfrog” Method
i-2 i-1 i i+1 i+2
Ex
t – Δt/2
i-1 1/2 i-1/2 i+1/2 i+1 1/2
Hy
t
i-2 i-1 i i+1 i+2
Ex
t +Δt/2
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
21. • In 3D, the E and H fields can be visualized as existing on separate
but interlaced grids over a cubic cell,
z
Ey
Ex Ex
Hz
Ey
Ex Ez
Ez
Hy
Hx
Ex
Hy “Yee cell”
Hx
Ex Ey Ex
Hz
Ey
y
x
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
22. • An upper bound is imposed on the simulation timestep due to
Courant-Freidrich-Levy1 (CFL) condition for finite-difference
solutions of the wave equation,
where c is the wave velocity, Δt is the timestep, and Δx, Δy, and Δz are
the spatial dimensions of each grid cell.
1R.
Courant, K. Friedrichs, and H. Lewy. “On the
Partial Difference Equations of Mathematical
Physics.” IBM Journal, pp 215-234, Mar. 1967
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
23. • EM wave problems are defined, in general, with OPEN or
UNBOUNDED domains that extend out to infinity.
• However, computationally impossible to store unlimited amount
of data required
Domain must be truncated so that it:
• Fully contains structure of interest.
• Resolves any region of interest within/around device.
• Allows for wave propagation while minimizing
reflections of outward traveling waves at boundaries.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
24. We have chosen to implement the Perfectly Matched Layer (PML)
absorbing boundary condition recently developed by Berenger1.
• Formulation involves a “field-splitting” approach
creating boundary layer that can:
absorb any kind of traveling wave.
regardless of direction of travel.
without reflection back into domain.
1J. P. Bérenger, “Perfectly matched layer for
the FDTD solution of wave-structure
interaction problems,” IEEE Trans. Antennas
Propagat., vol 44, pp. 110-117, Jan. 1996.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
25. • Berenger introduced (1) complex permittivity/permeability
(2) split the field components into 2 parts.
• This resulted in the following set of (12) equations,
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
27. • Introduction / Motivation
• Full Band Simulator
• Finite-Difference Time Domain Method
(FDTD) / Maxwell Solver
• Coupling of Maxwell/Monte Carlo
• Simulation results / Conclusions
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
28. Coupling FDTD solver to EMC
Initialize Device Initialize Device
Calculate Charge Calculate Current Density
Poisson Solver Maxwell Solver
Free Flight Free Flight
Particle Dynamics Particle Dynamics
No No
End of End of
Simulation? Simulation?
Yes Yes
Calculate Averages Calculate Averages
End End
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
29. Curl form of necessary Maxwell equations are:
The current density, J can be
calculated directly via temporal
and spatial evolution of charge
from Ensemble Monte Carlo.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
30. Current density is computed at every timestep using weighted summation
of particle velocities in each grid cell,
charge velocity
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
31. Determine carrier
distribution
EMC/CMC
Solver
Calculate current density
J(i,j,k)
Calculate E and H fields
using J(i,j,k)
Maxwell
Solver
Determine Lorentz Force
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
32. • Introduction / Motivation
• Full Band Simulator
• Finite-Difference Time Domain Method
(FDTD) / Maxwell Solver
• Coupling of Maxwell/Monte Carlo
• Simulation results / Conclusions
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
33. In experimental setup, a mode-locked Ti: Sapphire laser with a
pulse duration of 12fs, central photon frequency of 1.49eV, and bandwidth
of 120meV used to optically excite electron-hole pairs in GaAs and InP pin
Diodes with intrinsic region 500 nm long
1A. Leitenstorfer, S. Hunsche, J. Shah, M.C. Nuss, and
W.H. Knox: Phys. Rev. Lett. 82 5140 (1999).
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
34. 1A. Leitenstorfer, S. Hunsche, J. Shah, M.C. Nuss, and
W.H. Knox: Phys. Rev. Lett. 82 5140 (1999).
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
35. pin diode:
h
p+ i n+
VA
momentum space
EC
real space
-
EC h
EG
- +
EV
EFp
EV h
qVA
EFn h = EG+
+
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
36. EX=-VA/LX
empirical generation rate:
+ -
+ -
+ -
+ -
change in carrier density: + -
LX
ninj=5x1014 cm-3
tp = 10fs
t0 = 20 fs
t = 0.0167 fs
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
37. simulated region
p+ i n+
h
Ly EX=-VA/LX
+ -
+ -
LX +
+
-
- 10 grid cells
+ -
h = 1.49 eV
50 grid cells
Lx = 500 nm
Ly = 100 nm
Lz = 100 nm
Ne = Nh = 25,000
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
38. 500 nm 500 nm
PML
Region
300 nm Filament
GaAs
Air
Snapshot #2 at 480nm from left Snapshot #1 at 50nm from left y
GaAs
contact surface. contact surface.
x
z
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
39. Magnitude of Longitudinal Field (Ex) at 50 nm from contact surface.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
40. Transverse field (Ey) at 50 nm from Displacement of carriers vs. time
contact surface.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
41. Longitudinal field (Ex) at 50 nm from contact surface.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
42. 500 nm 500 nm
PML
Region
300 nm Filament
GaAs
Air
Snapshot #2 at 480nm from left Snapshot #1 at 50nm from left y
GaAs
contact surface. contact surface.
x
z
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
43. Transverse field (Ey) at 480 nm from contact surface.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
44. Simulation results for 100 kV/cm Simulation results due to Wigger et. al.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH
45. • Presented direct simulation and capture of THz
transient field patterns from simple device structure
using a fullband simulator coupled with a Maxwell solver.
• Demonstrated usefulness of Global Solver to model
EM characteristics of a simple device.
• Future work will involve implementation of FDTD
Method not constrained by timestep criterion.
Nanostructures Research Group
CENTER FOR SOLID STATE ELECTRONICS RESEARCH