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We present a new theoretical approach for the simulations of X-ray photoelectron spectra of strongly correlated molecular systems that combines multireference algebraic diagrammatic construction theory (MR-ADC) [J. Chem. Phys., 2018, 149,…

Chemical Physics · Physics 2022-05-31 Carlos E. V. de Moura , Alexander Yu. Sokolov

We present the development and implementation of the relativistic coupled cluster linear response theory (CC-LR) which allows the determination of molecular properties arising from time-dependent or time-independent electric, magnetic, or…

A new method is presented for describing vibrational effects in x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) using a combination of the classical Franck-Condon (FC) approximation and classical…

Materials Science · Physics 2017-12-20 Mathias P. Ljungberg

X-ray absorption spectroscopy (XAS) has gained popularity in recent years as it probes matter with high spatial and elemental sensitivity. However, the theoretical modelling of XAS is a challenging task since XAS spectra feature a fine…

Chemical Physics · Physics 2023-02-03 Lukas Konecny , Stanislav Komorovsky , Jan Vicha , Kenneth Ruud , Michal Repisky

We investigated whether a combination of k-space undersampling and variable density averaging enhances image quality for low-SNR MRI acquisitions. We implemented 3D Cartesian k-space prospective undersampling with a variable number of…

X-ray four-wave mixing signals generated in the $k_1 + k_2 - k_3$ phase-matching direction are simulated for N1s transitions in para-nitroanline and two-ring hydrocarbons disubstituted with an amine and a nitroso groups. The two-dimensional…

Atomic Physics · Physics 2008-11-20 Igor V. Schweigert , Shaul Mukamel

We present an implementation of a damped response framework for calculating resonant inelastic X-ray scattering (RIXS) at the equation-of-motion coupled cluster singles and doubles (CCSD) and second-order approximate coupled cluster singles…

We establish a rigorous density functional theory (DFT) framework for core-level X-ray absorption spectroscopy (XAS) by formulating a constrained search for core-excited states based on the Gunnarsson-Lundqvist theorem. Within this…

Materials Science · Physics 2025-11-25 Seokkyu An , Taisuke Ozaki

X-ray absorption near edge structure (XANES) spectroscopy is a powerful technique for characterizing the chemical state and symmetry of individual elements within materials, but requires collecting data at many energy points which can be…

Applied Physics · Physics 2025-04-25 Ming Du , Mark Wolfman , Chengjun Sun , Shelly D. Kelly , Mathew J. Cherukara

We present a comprehensive computational framework for reproducing the full X-ray absorption fine structure (XAFS) through quantum-chemical simulations. The near-edge region is accurately captured using an efficient implementation of…

Materials Science · Physics 2025-12-04 Philipp Hönicke , Yves Kayser , Pouya Partovi-Azar

Vibrationally resolved near-edge x-ray absorption spectra at the K-edge for a number of small molecules have been computed from anharmonic vibrational configuration interaction calculations of the Franck-Condon factors. The potential energy…

Chemical Physics · Physics 2021-02-03 Torsha Moitra , Diana Madsen , Ove Christiansen , Sonia Coriani

We present the numerical implementation of the time-dependent complete-active-space self-consistent-field (TD-CASSCF) method [Phys. Rev. A, 88, 023402 (2013)] for atoms driven by a strong linearly polarized laser pulse. The present…

X-ray photoemission (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy play an important role in investigating the structure and electronic structure of materials and surfaces. Ab-initio simulations provide crucial…

Materials Science · Physics 2020-10-21 Benedikt Klein , Samuel J. Hall , Reinhard J. Maurer

In this paper, a novel model-based distributed compressive sensing (DCS) algorithm is proposed. DCS exploits the inter-signal correlations and has the capability to jointly recover multiple sparse signals. Proposed approach is a Bayesian…

Signal Processing · Electrical Eng. & Systems 2020-10-19 Razieh Torkamani , Hadi Zayyani , Ramazan Ali Sadeghzadeh

We present a modification of the $\Delta$SCF method of calculating energies of excited states, in order to make it applicable to resonance calculations of molecules adsorbed on metal surfaces, where the molecular orbitals are highly…

Materials Science · Physics 2009-03-06 Jeppe Gavnholt , Thomas Olsen , Mads Engelund , Jakob Schiøtz

Measuring scattered light is central to many laser-based gas diagnostic techniques, e.g., coherent anti-Stokes Raman spectroscopy (CARS) and filtered Rayleigh scattering (FRS). To produce quantitative measurements with such techniques, a…

Computational Physics · Physics 2020-05-18 Gregory J. Hunt , Cody R. Ground , Robin L. Hunt

We formulate and implement the core-valence separated multireference equation-of-motion driven similarity renormalization group method (CVS-IP-EOM-DSRG) for simulating X-ray photoelectron spectra (XPS) of strongly correlated molecular…

Chemical Physics · Physics 2025-09-29 Shuhang Li , Zijun Zhao , Francesco A. Evangelista

Light trapping and radiation process from linear reciprocal photonic resonators is one of the fundamental processes in optical science and engineering. Recently, the concept of coherent virtual absorption (CVA) of light was introduced and…

Optics · Physics 2020-04-01 Q. Zhong , L. Simonson , T. Kottos , R. El-Ganainy

We present three schemes to go beyond the electric-dipole approximation in X-ray absorption spectroscopy calculations within a four-component relativistic framework. The first is based on the full semi-classical light-matter interaction…

Chemical Physics · Physics 2021-07-02 Nanna Holmgaard List , Timothé Romain Léo Melin , Martin van Horn , Trond Saue

Through temporal shaping of the excitation signal, the complex-frequency scattering zeros of a lossless structure can be accessed, enabling a storage-release mechanism referred to as coherent virtual absorption. Practical demonstrations of…