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Quasar absorption systems encode a wealth of information about the abundances, ionization structure, and physical conditions in intergalactic and circumgalactic media. Simple (often single-phase) photoionization models are frequently used…

To understand quantum optics experiments, we must perform calculations that consider the principal sources of noise, such as losses, spectral impurity and partial distinguishability. In both discrete and continuous variable systems, these…

Quantum Physics · Physics 2025-08-15 Jacob F. F. Bulmer , Javier Martínez-Cifuentes , Bryn A. Bell , Nicolás Quesada

Methods for electronic structure based on Gaussian and molecular orbital discretizations offer a well established, compact representation that forms much of the foundation of correlated quantum chemistry calculations on both classical and…

We introduce a novel and concise methodology to detect the parity of atomic and molecular orbitals based on photoelectron holography, which is more general than the existing schemes. It fully accounts for the Coulomb distortions of electron…

Cryogenic electron microscopy is widely used in structural biology, but its resolution is often limited by the dynamics of the macromolecule. Here, we developed a refinement protocol based on Gaussian mixture models that integrates particle…

Quantitative Methods · Quantitative Biology 2023-08-31 Muyuan Chen , Michael F. Schmid , Wah Chiu

We present a scalable implementation of the $GW$ approximation using Gaussian atomic orbitals to study the valence and core ionization spectroscopies of molecules. The implementation of the standard spectral decomposition approach to the…

Chemical Physics · Physics 2021-12-06 Daniel Mejia-Rodriguez , Alexander Kunitsa , Edoardo Aprà , Niranjan Govind

The total single-photon ionisation cross section was calculated for helium atoms in their ground state. Using a full configuration-interaction approach the photoionisation cross section was extracted from the complex-scaled resolvent. In…

Atomic Physics · Physics 2015-05-19 Alexander Stark , Alejandro Saenz

Gaussian bipartite states are basic tools for the realization of quantum information protocols with continuous variables. Their complete characterization is obtained by the reconstruction of the corresponding covariance matrix. Here we…

Quantum Physics · Physics 2016-04-27 D. Buono , G. Nocerino , V. D'Auria , A. Porzio , S. Olivares , M. G. A. Paris

We present a quantum algorithm for efficiently sampling transformed Gaussian random fields on $d$-dimensional domains, based on an enhanced version of the classical moving average method. Pointwise transformations enforcing boundedness are…

Quantum Physics · Physics 2025-08-20 Matthias Deiml , Daniel Peterseim

Absorption of infrared and visible radiation from stellar emission spectra by the negatively charged hydrogen ions H$^{-}$ is considered. The explicit formula for the photodetachment cross-section of the negatively charged hydrogen ion(s)…

Solar and Stellar Astrophysics · Physics 2015-06-01 Alexei M. Frolov

The complex Kohn variational method is extended to compute light-driven electronic transitions between continuum wavefunctions in atomic and molecular systems. This development enables the study of multiphoton processes in the perturbative…

Atomic Physics · Physics 2018-08-15 Nicolas Douguet , Barry I. Schneider , Luca Argenti

Calibrating for direction-dependent ionospheric distortions in visibility data is one of the main technical challenges that must be overcome to advance low-frequency radio astronomy. In this paper, we propose a novel probabilistic,…

Instrumentation and Methods for Astrophysics · Physics 2020-01-15 J. G. Albert , M. S. S. L. Oei , R. J. van Weeren , H. T. Intema , H. J. A. Röttgering

An efficient all-electron G$^0$W$^0$ method and a quasiparticle selfconsistent GW (QSGW) method for molecules are proposed in the molecular orbital space with the full random phase approximation. The convergence with basis set is examined.…

Mesoscale and Nanoscale Physics · Physics 2015-03-17 San-Huang Ke

In quantum computation with continous-variable systems, quantum advantage can only be achieved if some non-Gaussian resource is available. Yet, non-Gaussian unitary evolutions and measurements suited for computation are challenging to…

Quantum Physics · Physics 2017-06-13 Francesco Arzani , Nicolas Treps , Giulia Ferrini

The pencil-beam model is valid only when elementary Gaussian beams are small enough with respect to lateral heterogeneity of a medium, which is not always the case in heavy charged particle radiotherapy. This work addresses a solution for…

Medical Physics · Physics 2009-03-17 Nobuyuki Kanematsu , Masataka Komori , Shunsuke Yonai , Azusa Ishizaki

We study two classes of radial integrals involving a product of bound and continuum one-electron states. Using a representation of the continuum part with an expansion on complex Gaussian Type Orbitals, such integrals can be performed…

Chemical Physics · Physics 2024-05-17 Abdallah Ammar , Arnaud Leclerc , Lorenzo Ugo Ancarani

We present a comparison of various approximations to self-consistency in the GW method, including the one-shot G0W0 method, different quasiparticle self-consistency schemes, and the fully self-consistent GW (scGW) approach. To ensure an…

Strongly Correlated Electrons · Physics 2025-10-17 Gaurav Harsha , Vibin Abraham , Ming Wen , Dominika Zgid

The rich information content of measurements in the molecular frame rather than the laboratory frame has motivated the development of several methods for aligning gas phase molecules in space. Even so, for asymmetric tops the problem of…

Atomic Physics · Physics 2016-11-23 Varun Makhija , Xiaoming Ren , Drue Gockel , Anh-Thu Le , Vinod Kumarappan

Hyperspherical partial wave approach has been applied here in the study of double photoionization of the helium atom for equal energy sharing geometry at 20 eV excess energy. Calculations have been done both in length and velocity gauges…

Atomic Physics · Physics 2009-11-10 J. N. Das , K. Chakrabarti , S. Paul

Choosing a basis set is the first step of a quantum chemistry calculation and it sets its maximum accuracy. This choice of orbitals is limited by strong technical constraints as one must be able to compute a large number of six dimensional…

Strongly Correlated Electrons · Physics 2026-02-04 Nicolas Jolly , Yuriel Núñez Fernández , Xavier Waintal