Calculated photoionization cross sections using Quantemol-N

Brigg, Will; Harvey, Alex G.; Dzarasova, Anna; Mohr, Sebastian; Morales, Felipe; Smirnova, Olga; Tennyson, Jonathan

doi:10.7567/jjap.54.06ga02

Cited by 12 publications

(8 citation statements)

References 48 publications

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“…The capacity to calculate single photon ionization/recombination was added to the UKRmol suite [11] since the last publication detailing its code base in 2012 [8] and was used, via the Quantemol implementation [78], for a number of photodetachment studies [79]. The common need to treat higher photoelectron energies in photoionization/recombination applications provided one of the motivations for the development of UKRmol+.…”

Section: Photoionization Calculationsmentioning

confidence: 99%

UKRmol+: A suite for modelling electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method

Mašín

Benda

Gorfinkiel

et al. 2020

Computer Physics Communications

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122

136

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UKRmol+ is a new implementation of the UK R-matrix electron-molecule scattering code. Key features of the implementation are the use of quantum chemistry codes such as Molpro to provide target molecular orbitals; the optional use of mixed Gaussian -B-spline basis functions to represent the continuum and improved configuration and Hamiltonian generation. The code is described, and examples covering electron collisions from a range of targets, positron collisions and photionisation are presented. The codes are freely available as a tarball from Zenodo. [2] A. Brown et al RMT: R-matrix with time-dependence. Solving the semirelativistic, time-dependent Schrödinger equation for general, multi-electron atoms and molecules in intense, ultrashort, arbitrarily polarized laser pulses., Computer Phys. Comm., submitted

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Section: Photoionization Calculationsmentioning

confidence: 99%

UKRmol+: A suite for modelling electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method

Mašín

Benda

Gorfinkiel

et al. 2020

Computer Physics Communications

Self Cite

122

136

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“…More recent developments involved the extension of calculations to high energies using the so-called BEf procedure of Kim [22] and the spherical complex optical potential (SCOP) method [23][24][25]. Recent releases of QN also feature an implementation of the UKRMol photoionization model [26].…”

Section: Introductionmentioning

confidence: 99%

Quantemol Electron Collisions (QEC): An Enhanced Expert System for Performing Electron Molecule Collision Calculations Using the R-Matrix Method

Cooper

Tudorovskaya

Mohr

et al. 2019

Atoms

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Collisions of low energy electrons with molecules are important for understanding many aspects of the environment and technologies. Understanding the processes that occur in these types of collisions can give insights into plasma etching processes, edge effects in fusion plasmas, radiation damage to biological tissues and more. A radical update of the previous expert system for computing observables relevant to these processes, Quantemol-N, is presented. The new Quantemol Electron Collision (QEC) expert system simplifyies the user experience, improving reliability and implements new features. The QEC graphical user interface (GUI) interfaces the Molpro quantum chemistry package for molecular target setups, and the sophisticated UKRmol+ codes to generate accurate and reliable cross-sections. These include elastic cross-sections, super elastic cross-sections between excited states, electron impact dissociation, scattering reaction rates, dissociative electron attachment, differential cross-sections, momentum transfer cross-sections, ionization cross sections, and high energy electron scattering cross-sections. With this new interface we will be implementing dissociative recombination estimations, vibrational excitations for neutrals and ions, and effective core potentials in the near future.

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“…The approach is computationally very demanding but has been applied with success to H 2 + and H 2 . Recently, they have been actively pursuing extension of the algorithms to general polyatomics. , In principle, the R-matrix approach , is capable of describing the ionization process of medium-size molecules, and it shares some common ideas with the LCAO B-spline methods that we have developed. − Recent efforts directed toward the extension of the UKRmol code to compute low-energy photoionization and recombination cross sections, − has given very encouraging results. Furthermore, the full CC expansion has been recently implemented by Scrinzi et al, based on a quantum chemistry multireference configuration interaction (MRCI) description of initial and target states, plus localized correlation functions, and finite elements for the unbound electron, and the method has been applied with success to the strong-field ionization of atoms and small molecules. − …”

Section: Introductionmentioning

confidence: 99%

A Multichannel Least-Squares B-Spline Approach to Molecular Photoionization: Theory, Implementation, and Applications within the Configuration–Interaction Singles Approximation

Toffoli

Decleva

2016

J. Chem. Theory Comput.

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We describe, in detail, a basis set approach to the multichannel scattering problem. The full set of linearly independent scattering states at each prefixed energy of the continuum spectrum can be obtained via a least-squares approach. To test the algorithm in a concrete setup, we report a parallel implementation of the close-coupling method in which the final states are treated within the configuration-interaction singles (CIS) approximation. The method requires, as input, a set of orthonormal orbitals, obtained from any quantum chemistry package. A one-center expansion (OCE) basis set consisting of products of radial B-splines and symmetry adapted angular functions is then used to expand the continuum electron wave function. To assess the quality of the CIS approximation, we compute total and partial cross sections and angular asymmetry parameters for the photoionization of a selection of closed-shell atoms (He, Ne, and Ar), H, HO, and ethylene. Results are compared with the experimental data and with theoretical predictions obtained with time-dependent density functional theory (TDDFT). It is seen that, generally, the photoionization observables obtained at the CIS level compare well with TDDFT predictions. The same basis can be employed to describe molecular multiphoton or strong field ionization.

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Calculated photoionization cross sections using Quantemol-N

Cited by 12 publications

References 48 publications

UKRmol+: A suite for modelling electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method

UKRmol+: A suite for modelling electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method

Quantemol Electron Collisions (QEC): An Enhanced Expert System for Performing Electron Molecule Collision Calculations Using the R-Matrix Method

A Multichannel Least-Squares B-Spline Approach to Molecular Photoionization: Theory, Implementation, and Applications within the Configuration–Interaction Singles Approximation

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