quick dft tour of electron energy loss spectrum (eels)
TRANSCRIPT
By
Shruba Gangopadhyay
Email shrubagmailcom
Basics of EELS Material exposed to a beam of electrons with a
known narrow range of kinetic energies
Electrons will undergo inelastic scattering which
means that they lose energy
Inelastic interactions include
phonon excitations
inter and intra band transitions
plasmon excitations
inner shell ionizations
2
Atomic amp Electronic Structure
STEM + EELS makes
essential connection
between physical amp
electronic structure
both at atomic
resolution
Electron Energy
Loss Spectrometer
Annular Dark Field
(ADF) detector
yx
Atomic Diameter
Electron Probe
Incre
asi
ng
energ
y loss
We can have an estimate of beam energy ranges from httppeopleccmrcornelledu~davidmWEELSindexhtml
httppc-webcemesfreelsdbindexphppage=searchphp
EELS hellip(Theory)
THEORY OF EELS The EELS (and XAS) spectral shape is given by the Fermi golden rule
The core electron is excited to an empty state where at the edge the lowest empty
state (allowed by the selection rules) is reached
As such one essentially probes the empty density of states in the presence of the
core hole Calculations to obtain a quantitative picture of the empty states can be
performed with DFT based codes
A double differential scattering cross-section is calculated by
summing over all possible transitions between initial and final
states each described by a Fermirsquos golden rule
4
5
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Basics of EELS Material exposed to a beam of electrons with a
known narrow range of kinetic energies
Electrons will undergo inelastic scattering which
means that they lose energy
Inelastic interactions include
phonon excitations
inter and intra band transitions
plasmon excitations
inner shell ionizations
2
Atomic amp Electronic Structure
STEM + EELS makes
essential connection
between physical amp
electronic structure
both at atomic
resolution
Electron Energy
Loss Spectrometer
Annular Dark Field
(ADF) detector
yx
Atomic Diameter
Electron Probe
Incre
asi
ng
energ
y loss
We can have an estimate of beam energy ranges from httppeopleccmrcornelledu~davidmWEELSindexhtml
httppc-webcemesfreelsdbindexphppage=searchphp
EELS hellip(Theory)
THEORY OF EELS The EELS (and XAS) spectral shape is given by the Fermi golden rule
The core electron is excited to an empty state where at the edge the lowest empty
state (allowed by the selection rules) is reached
As such one essentially probes the empty density of states in the presence of the
core hole Calculations to obtain a quantitative picture of the empty states can be
performed with DFT based codes
A double differential scattering cross-section is calculated by
summing over all possible transitions between initial and final
states each described by a Fermirsquos golden rule
4
5
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Atomic amp Electronic Structure
STEM + EELS makes
essential connection
between physical amp
electronic structure
both at atomic
resolution
Electron Energy
Loss Spectrometer
Annular Dark Field
(ADF) detector
yx
Atomic Diameter
Electron Probe
Incre
asi
ng
energ
y loss
We can have an estimate of beam energy ranges from httppeopleccmrcornelledu~davidmWEELSindexhtml
httppc-webcemesfreelsdbindexphppage=searchphp
EELS hellip(Theory)
THEORY OF EELS The EELS (and XAS) spectral shape is given by the Fermi golden rule
The core electron is excited to an empty state where at the edge the lowest empty
state (allowed by the selection rules) is reached
As such one essentially probes the empty density of states in the presence of the
core hole Calculations to obtain a quantitative picture of the empty states can be
performed with DFT based codes
A double differential scattering cross-section is calculated by
summing over all possible transitions between initial and final
states each described by a Fermirsquos golden rule
4
5
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
EELS hellip(Theory)
THEORY OF EELS The EELS (and XAS) spectral shape is given by the Fermi golden rule
The core electron is excited to an empty state where at the edge the lowest empty
state (allowed by the selection rules) is reached
As such one essentially probes the empty density of states in the presence of the
core hole Calculations to obtain a quantitative picture of the empty states can be
performed with DFT based codes
A double differential scattering cross-section is calculated by
summing over all possible transitions between initial and final
states each described by a Fermirsquos golden rule
4
5
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
5
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
When we need core hole approximation
When you have good energy resolution (lt1 eV)
When screening is poor
Metals (small) semiconductors(medium) ionic (huge)
The effect is larger on anions than cations
More noticeable in nanoparticles and clusters than bulk
Batsonrsquos Rule core hole effects are more pronounced when The excited electron is confined near the core hole (It shouldnrsquot work but it
does)
Atoms surrounded by strong scatterers (often nodeless valence wavefunctions1s 2p 3dhellip) (eg Si in SiOx Al in NiAl TiB2 out of plane)
6
In Wien 2k we can only simulate electron loss near-edge structure (ELNES) rdquo features in the spectrum with energy loss E = Ec to Ec + 50 eV (by definition) It contains
information on local density of empty states oxidation state
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
How to simulate Core Hole in Wien2kNo core hole (= ground state sudden approximation)
1048708 Z+1 approximation (eg replace C by N)
1048708 Remove 1 core electron add 1 electron to conduction band
1048708 Remove 1 core electron add 1 electron as uniform background
charge
More localized the core hole the bigger the error7
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
How to simulate EELS in in Wien2k
(TELNES)Construct a supercell and perform an SCF
(need good amount of K points)
If excited states required prepare another input by reseting energy range and recalculate valence bands
Compute Valence electron densities from eigenvectors
Calculate eigenvalues and corresponding partial charges
Prepare input for EELS
use of beam energy and other angular parameters
This results The differential cross section is either a function of energy (ELNES ( the output of
Wien2k) integrated over impulse transfer) or a function of impulse transfer (ELNES integrated
over energy loss E) which shows the angular behavior of scattering8
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Available softwares and pros and cons
Wien2k Quantum ESPRESSO
(External suite SaX)
Telnes (code) SaX external code
Double differential
scattering cross
section on a
grid of energy loss
Macroscopic
dielectric tensor
within the Random
Phase Approximation
with or without
excitonic effects as a
function of energy
Computationally
less expensive
Very expensive
Applied to various
systems
Not too many
published papers
Band structure codes
PARATEC (Cabaret et al2007Gaudryetal2005)
PWSCF(Cabaret et al2010Juhin et al2010)
CASTEP(Gao et al2008)
WIEN2K(Schwarz et al 2002)
Real space multiple scattering codes
FDMNES (Joly 2003)
FEFF(Rehr andAlbers2000)
Molecular DFT codes
STOBE(Kolczewski andHermann2005)
ORCA (George etal2008)
9
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Literature Review
As per my understanding the advantages of Wien2k is
Can handle large system
No need to worry about core hole pseudopotentials
Applied to TM and Lanthanide including Magnetic transitions
Parallel implementation
Option of using relativistic correction
User friendly interface for generating input files
Extremely active user forum
10
Wien2k VO2 (crystal) LiMn2O4 TiO2 ZrO2 Nb1-xMgxB2 LixTiP4 (x=2-
11) LiK edge in Li Li2O and LiMn2O4 Si layers
ferroelectric transition in BaTiO3
helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip TiC TiN
Quantum
ESPRESSO
Boron Nitrogen doped graphene different phases of Al2O3
VASP No direct implementation (derived from DOS) C60
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Simulated EELS for K edge EELS of
Carbon in TiC using (2x2x2) supercell
1000 k points
100 k points
I did not use any core hole approximation in
this calculation11
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12
Sources
Wien2k manual Tutorial from 2007 PSU
workshop
SaX manual
Presentation from David Mullers summer
school pdf
Calculations are performed in NERSC using
Wien2k v101 and Telnes2
12