scholarly journals Dyson Orbitals within the fc-CVS-EOM-CCSD Framework: Theory and Application to X-ray Photoelectron Spectroscopy of Ground and Excited States

2019 ◽  
Author(s):  
Marta L. Vidal ◽  
Anna Krylov ◽  
Sonia Coriani
Keyword(s):  
Excited States ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Equation Of Motion ◽  
Photoelectron Spectra ◽  
Coupled Cluster ◽  
Time Resolved ◽  
X Ray ◽  
Target States

We report on the implementation of Dyson orbitals within the recently introduced frozen-core (fc) core-valence separated (CVS) equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method, which enables efficient and reliable characterization of core-level states. The ionization potential (IP) variant of fc-CVS-EOM-CCSD, in which the EOM target states have one electron less than the reference, gives access to core-ionized states thus enabling modeling of<br><div>X-ray photoelectron spectra (XPS) and its time-resolved variant (TR-XPS). Dyson orbitals are reduced quantities that can be interpreted as correlated states of the ejected/attached electron; they enter the expressions of various experimentally relevant quantities. In the context of photoelectron spectroscopy, Dyson orbitals can be used to estimate the strengths of photoionization transitions. We illustrate the utility of Dyson orbitals and fc-CVS-EOM-IP-CCSD by calculating XPS of the ground state of adenine and TR-XPS of the excited states of uracil.</div>

scholarly journals Dyson Orbitals within the fc-CVS-EOM-CCSD Framework: Theory and Application to X-ray Photoelectron Spectroscopy of Ground and Excited States

2019 ◽  
Author(s):  
Marta L. Vidal ◽  
Anna Krylov ◽  
Sonia Coriani
Keyword(s):  
Excited States ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Equation Of Motion ◽  
Photoelectron Spectra ◽  
Coupled Cluster ◽  
Time Resolved ◽  
X Ray ◽  
Target States

We report on the implementation of Dyson orbitals within the recently introduced frozen-core (fc) core-valence separated (CVS) equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method, which enables efficient and reliable characterization of core-level states. The ionization potential (IP) variant of fc-CVS-EOM-CCSD, in which the EOM target states have one electron less than the reference, gives access to core-ionized states thus enabling modeling of<br><div>X-ray photoelectron spectra (XPS) and its time-resolved variant (TR-XPS). Dyson orbitals are reduced quantities that can be interpreted as correlated states of the ejected/attached electron; they enter the expressions of various experimentally relevant quantities. In the context of photoelectron spectroscopy, Dyson orbitals can be used to estimate the strengths of photoionization transitions. We illustrate the utility of Dyson orbitals and fc-CVS-EOM-IP-CCSD by calculating XPS of the ground state of adenine and TR-XPS of the excited states of uracil.</div>

scholarly journals Dyson Orbitals within the fc-CVS-EOM-CCSD Framework

2019 ◽  
Author(s):  
Marta L. Vidal ◽  
Anna Krylov ◽  
Sonia Coriani
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Equation Of Motion ◽  
Photoelectron Spectra ◽  
Coupled Cluster ◽  
Time Resolved ◽  
X Ray ◽  
Ccsd Method

We report on the implementation and illustrative applications of Dyson orbitals within the recently proposed frozen-core (fc) core-valence separated (CVS) equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method, which enables efficient and accurate characterization of core-ionized states. Dyson orbitals are reduced quantities that can be interpreted as correlated states of the ejected/attached electron.<br>Dyson orbitals enter the expressions of various experimental observables, such as photoionization cross sections; thus, they are necessary for modeling photoelectron spectra.<br>Here we discuss the simulations of X-ray photoelectron spectra (XPS) and propose an approach to simulate time-resolved (TR-)XPS for probing excited states. <br>As illustrative examples, we present the simulation of the XPS of the ground state of adenine and of TR-XPS of the excited states of uracil.

scholarly journals Dyson orbitals within the fc-CVS-EOM-CCSD framework: theory and application to X-ray photoelectron spectroscopy of ground and excited states

2020 ◽  
Vol 22 (5) ◽  
pp. 2693-2703 ◽  
Author(s):  
Marta L. Vidal ◽  
Anna I. Krylov ◽  
Sonia Coriani
Keyword(s):  
Excited States ◽  
Photoelectron Spectroscopy ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Ionization Energies ◽  
X Ray

Ionization energies and Dyson orbitals within frozen-core core–valence separated equation-of-motion coupled cluster singles and doubles (fc-CVS-EOM-CCSD) enable efficient and reliable calculations of standard XPS and of UV-pump/XPS probe spectra.

scholarly journals Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 202
Author(s):  
Miranda Martinez ◽  
Anil R. Chourasia
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Increasing Trend ◽  
Substrate Temperatures ◽  
Beam Technique

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO2 upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

scholarly journals Equation-of-Motion Coupled-Cluster Theory to Model L-edge X-Ray Absorption and Photoelectron Spectra

2020 ◽  
Author(s):  
Marta Lopez Vidal ◽  
Pavel Pokhilko ◽  
Anna Krylov ◽  
Sonia Coriani
Keyword(s):  
Small Molecules ◽  
Particle Density ◽  
Equation Of Motion ◽  
Wave Functions ◽  
Model Systems ◽  
Photoelectron Spectra ◽  
Coupled Cluster ◽  
Coupled Cluster Theory ◽  
X Ray ◽  
X Ray Absorption

We present an extension of the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) theory for computing x-ray L-edge spectra, both in the absorption (XAS) and photoelectron (XPS) regimes. The approach is based on the perturbative evaluation of spin-orbit couplings using the Breit-Pauli Hamiltonian and nonrelativistic wave-functions described by the fc-CVS-EOM-CCSD ansatz (EOM-CCSD within the frozen-core core-valence separated (fc-CVS) scheme). The formalism is based on spinless one-particle density matrices. The approach is illustrated by modeling XAS and XPS of several model systems ranging from argon atoms to small molecules containing sulfur and silicon.

scholarly journals Equation-of-Motion Coupled-Cluster Theory to Model L-edge X-Ray Absorption and Photoelectron Spectra

2020 ◽  
Author(s):  
Marta Lopez Vidal ◽  
Pavel Pokhilko ◽  
Anna Krylov ◽  
Sonia Coriani
Keyword(s):  
Small Molecules ◽  
Particle Density ◽  
Equation Of Motion ◽  
Wave Functions ◽  
Model Systems ◽  
Photoelectron Spectra ◽  
Coupled Cluster ◽  
Coupled Cluster Theory ◽  
X Ray ◽  
X Ray Absorption

We present an extension of the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) theory for computing x-ray L-edge spectra, both in the absorption (XAS) and photoelectron (XPS) regimes. The approach is based on the perturbative evaluation of spin-orbit couplings using the Breit-Pauli Hamiltonian and nonrelativistic wave-functions described by the fc-CVS-EOM-CCSD ansatz (EOM-CCSD within the frozen-core core-valence separated (fc-CVS) scheme). The formalism is based on spinless one-particle density matrices. The approach is illustrated by modeling XAS and XPS of several model systems ranging from argon atoms to small molecules containing sulfur and silicon.

Photoionization dynamics in CS fragmented from CS2 studied by high-resolution photoelectron spectroscopy

2004 ◽  
Vol 82 (6) ◽  
pp. 744-749
Author(s):  
Anouk M Rijs ◽  
Ellen HG Backus ◽  
Cornelis A de Lange
Keyword(s):  
High Resolution ◽  
Triplet State ◽  
Key Words ◽  
Excited States ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Electronic States ◽  
Reactive Intermediates ◽  
Photoelectron Spectra ◽  
Singlet Ground State

The photoionization dynamics of CS have been studied using high-resolution laser photoelectron spectroscopy. The photodissociation of CS2 at ~308 nm results in highly rotationally excited CS in its X1Σ+ singlet ground state, as well as in rotationally cold CS in the excited a3Π triplet state. The ground-state CS fragments are formed together with sulfur in its 3P, 1D, and 1S electronic states; triplet CS is produced in coincidence with ground-state sulfur (3P). In both channels the photoelectron spectra are dominated by Δv = 0 propensity, but transitions involving Δv = 1 and 2 are also observed. Key words: photoelectron spectroscopy, photoionization, photodissociation, excited states, reactive intermediates.

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