scholarly journals Resonant Inelastic X-ray Scattering and Nonesonant X-ray Emission Spectra from Coupled-Cluster (Damped) Response Theory

2018 ◽  
Vol 15 (1) ◽  
pp. 520-528 ◽  
Author(s):  
Rasmus Faber ◽  
Sonia Coriani
Keyword(s):  
Emission Spectra ◽  
Coupled Cluster ◽  
Response Theory ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

scholarly journals Resonant Inelastic X-Ray Scattering and Non Resonant X-ray Emission Spectra from Coupled-Cluster (Damped) Response Theory

2018 ◽  
Author(s):  
Rasmus Faber ◽  
Sonia Coriani
Keyword(s):  
Gas Phase ◽  
Emission Spectra ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Simple Scheme ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Spectra ◽  
Ray Scattering

A coupled cluster protocol rooted in damped response theory is presented for computing Resonant Inelastic X-Ray Scattering spectra of molecules in gas-phase. Working equations are reported for both linear (i.e., equation-of-motion) and non-linear<br>parametrizations of the coupled-cluster wavefunction response. A simple scheme to<br>compute non-resonant X-ray emission spectra is also proposed. Illustrative results are<br>presented for water.

scholarly journals Resonant Inelastic X-Ray Scattering and Non Resonant X-ray Emission Spectra from Coupled-Cluster (Damped) Response Theory

2018 ◽  
Author(s):  
Rasmus Faber ◽  
Sonia Coriani
Keyword(s):  
Gas Phase ◽  
Emission Spectra ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Simple Scheme ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Spectra ◽  
Ray Scattering

A coupled cluster protocol rooted in damped response theory is presented for computing Resonant Inelastic X-Ray Scattering spectra of molecules in gas-phase. Working equations are reported for both linear (i.e., equation-of-motion) and non-linear<br>parametrizations of the coupled-cluster wavefunction response. A simple scheme to<br>compute non-resonant X-ray emission spectra is also proposed. Illustrative results are<br>presented for water.

scholarly journals How to stay out of trouble in RIXS calculations within equation-of-motion coupled-cluster damped response theory? Safe hitchhiking in the excitation manifold by means of core–valence separation

2020 ◽  
Vol 22 (5) ◽  
pp. 2629-2641 ◽  
Author(s):  
Kaushik D. Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna I. Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Ray Scattering

We present a novel approach with robust convergence of the response equations for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework.

scholarly journals How to Stay out of Trouble in RIXS Calculations Within Equation-of-Motion Coupled-Cluster Damped Response Theory? Safe Hitchhiking in the Excitation Manifold by Means of Core-Valence Separation

2019 ◽  
Author(s):  
Kaushik Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Response Equation ◽  
Divergent Behavior

<div>We present a novel approach for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework. The approach is based on recasting the sum-over-state expressions for RIXS moments into a compact form by using damped response theory. Damped response formalism allows one to circumvent problems of divergent behavior of the response equation in the resonant regime. However, the convergence of response equations in the X-ray frequency range is often erratic due to the resonant nature of the virtual core-excited states embedded in the valence ionization continuum. We demonstrate that this problematic behavior can be avoided by extending the core-valence separation (CVS) scheme, which decouples the valence-occupied and core-occupied excitation manifolds, into the response domain. The accuracy of the CVS-enabled damped response theory, implemented within the EOM-EE-CCSD (EOM-CC for excitation energies with single and double excitations) framework, is assessed by comparison against damped EOM-EE-CCSD response calculations. The capabilities of the new approach are illustrated by calculations of RIXS cross sections for benzene and benzene radical cation.</div>

scholarly journals Ultrafast X-ray Photochemistry at European XFEL: Capabilities of the Femtosecond X-ray Experiments (FXE) Instrument

2020 ◽  
Vol 10 (3) ◽  
pp. 995 ◽  
Author(s):  
Dmitry Khakhulin ◽  
Florian Otte ◽  
Mykola Biednov ◽  
Christina Bömer ◽  
Tae-Kyu Choi ◽  
...  
Keyword(s):  
Structural Information ◽  
Emission Spectra ◽  
Photochemical Reactions ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Transient Intermediates ◽  
X Ray Absorption ◽  
Ray Methods ◽  
Ray Scattering

Time-resolved X-ray methods are widely used for monitoring transient intermediates over the course of photochemical reactions. Ultrafast X-ray absorption and emission spectroscopies as well as elastic X-ray scattering deliver detailed electronic and structural information on chemical dynamics in the solution phase. In this work, we describe the opportunities at the Femtosecond X-ray Experiments (FXE) instrument of European XFEL. Guided by the idea of combining spectroscopic and scattering techniques in one experiment, the FXE instrument has completed the initial commissioning phase for most of its components and performed first successful experiments within the baseline capabilities. This is demonstrated by its currently 115 fs (FWHM) temporal resolution to acquire ultrafast X-ray emission spectra by simultaneously recording iron Kα and Kβ lines, next to wide angle X-ray scattering patterns on a photoexcited aqueous solution of [Fe(bpy)3]2+, a transition metal model compound.

scholarly journals How to Stay out of Trouble in RIXS Calculations Within the Equation-of-Motion Coupled-Cluster Damped Response Theory Framework? Safe Hitchhiking in the Excitation Manifold by Means of Core-Valence Separation

2019 ◽  
Author(s):  
Kaushik Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Response Equation ◽  
Divergent Behavior

<div>We present a novel approach for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework. The approach is based on recasting the sum-over-state expressions for RIXS moments into a compact form by using damped response theory. Damped response formalism allows one to circumvent problems of divergent behavior of the response equation in the resonant regime. However, the convergence of response equations in the X-ray frequency range is often erratic due to the resonant nature of the virtual core-excited states embedded in the valence ionization continuum. We demonstrate that this problematic behavior can be avoided by extending the core-valence separation (CVS) scheme, which decouples the valence-occupied and core-occupied excitation manifolds, into the response domain. The accuracy of the CVS-enabled damped response theory, implemented within the EOM-EE-CCSD (EOM-CC for excitation energies with single and double excitations) framework, is assessed by comparison against damped EOM-EE-CCSD response calculations. The capabilities of the new approach are illustrated by calculations of RIXS cross sections for benzene and benzene radical cation.</div>

Calculation of X-ray scattering intensities by means of the coupled cluster singles and doubles model

2001 ◽  
Vol 22 (13) ◽  
pp. 1315-1320 ◽  
Author(s):  
Noboru Watanabe ◽  
Yohei Kamata ◽  
Kota Yamauchi ◽  
Yasuo Udagawa
Keyword(s):  
Coupled Cluster ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Preparation, structural characterization, and luminescence properties of Eu3+-doped nanocrystalline ZrO2

2005 ◽  
Vol 20 (10) ◽  
pp. 2780-2791 ◽  
Author(s):  
A. Speghini ◽  
M. Bettinelli ◽  
P. Riello ◽  
S. Bucella ◽  
A. Benedetti
Keyword(s):  
Sol Gel ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
X Ray ◽  
Preparation Conditions ◽  
X Ray Scattering ◽  
Decay Times ◽  
Zirconia Nanopowders ◽  
Hydrolysis Of ◽  
Ray Scattering

Eu3+-doped zirconia nanopowders were prepared by the sol-gel technique using two different methods, based on the hydrolysis of zirconium n-propoxide, producing tetragonal and monoclinic zirconia under different preparation conditions. A detailed microstructure characterization was performed through wide angle x-ray scattering, small angle x-ray scattering, trasmission electron microscopy, and nitrogen physisorption measurements. The possible influence of the zirconia crystalline phases and particle sizes on the luminescence properties of the lanthanide ion was investigated. A detailed analysis of the emission spectra of the samples suggested that the dopant Eu3+ ions replace the Zr4+ ions in the zirconia crystal lattice. Moreover, samples prepared by the two different methods were characterized by different decay times of the Eu3+ ion luminescence.

scholarly journals How to Stay out of Trouble in RIXS Calculations Within Equation-of-Motion Coupled-Cluster Damped Response Theory? Safe Hitchhiking in the Excitation Manifold by Means of Core-Valence Separation

2019 ◽  
Author(s):  
Kaushik Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Response Equation ◽  
Divergent Behavior

<div>We present a novel approach for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework. The approach is based on recasting the sum-over-state expressions for RIXS moments into a compact form by using damped response theory. Damped response formalism allows one to circumvent problems of divergent behavior of the response equation in the resonant regime. However, the convergence of response equations in the X-ray frequency range is often erratic due to the resonant nature of the virtual core-excited states embedded in the valence ionization continuum. We demonstrate that this problematic behavior can be avoided by extending the core-valence separation (CVS) scheme, which decouples the valence-occupied and core-occupied excitation manifolds, into the response domain. The accuracy of the CVS-enabled damped response theory, implemented within the EOM-EE-CCSD (EOM-CC for excitation energies with single and double excitations) framework, is assessed by comparison against damped EOM-EE-CCSD response calculations. The capabilities of the new approach are illustrated by calculations of RIXS cross sections for benzene and benzene radical cation.</div>

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Sign in / Sign up

Export Citation Format

Share Document