Journal ArticleDOI
Modeling Nonresonant X-ray Emission of Second- and Third-Period Elements without Core-Hole Reference States and Empirical Parameters.
Bibek Samal,Vamsee K. Voora +1 more
TLDR
In this article , a scalar relativistic (sr) generalized Kohn-Sham semi-canonical projected random phase approximation (GKS-spRPA) method was proposed to estimate X-ray emission (XE) energies and oscillator strengths.Abstract:
Nonresonant X-ray emission (XE) energies and oscillator strengths are obtained using the effective potential of the generalized Kohn-Sham semi-canonical projected random phase approximation (GKS-spRPA) method. XE energies are estimated as a difference between the valence and core ionization eigenvalues, while the oscillator strengths are obtained within a frozen orbital approximation. This straightforward approach provides accurate XE energies without any need for core-hole reference states, empirical shifting parameters, or tuning of density functionals. To account for relativistic corrections to the core orbitals, we have formulated a scalar relativistic (sr) GKS-spRPA approach based on the spin-free X2C one-electron Hamiltonian. The sr-GKS-spRPA method provides highly reliable XE energies using uncontracted basis-sets on atoms where the core-hole is created prior to emission. For the largest basis-sets used in our study, using completely uncontracted polarized core-valence Dunning basis-sets, the mean absolute errors (MAEs) are within 0.7 eV compared to experimental reference values for a test-set consisting of 27 valence-to-core XE energies of molecules with second- and third-period elements. Considering a balance of accuracy and computational effort, we recommend the use of s-uncontracted def2-TZVP for second-period and all-uncontracted def2-TZVP for third-period elements. For this recommended basis-set, the MAE is 0.2 eV. The analytically continued sr-GKS-spRPA approach, with an O(N4) computational cost, enables efficient computation of XE spectra of molecules such as S8 and C60 with several core-hole states.read more
Citations
More filters
Journal ArticleDOI
TURBOMOLE: Today and Tomorrow.
Yannick J. Franzke,Christof Holzer,Josefine H Andersen,Tomislav Begušić,Florian Bruder,Sonia Coriani,Fabio Della Sala,Eduardo Fabiano,D. A. Fedotov,Susanne Fürst,Sebastian Gillhuber,Robin Grotjahn,Martin Kaupp,Max Kehry,Marjan Krstić,Fabian Mack,Sourav Majumdar,Brian Nguyen,Shane M. Parker,Fabian Pauly,Ansgar Pausch,Eva Perlt,Gabriel S. Phun,Dmitrij Rappoport,Bibek Samal,Tim Schrader,Manas Sharma,Enrico Tapavicza,R. S. Treß,Vamsee K. Voora,Artur Wodyński,Jason M. Yu,Benedikt Zerulla,Filipp Furche,Christof Hättig,Marek Sierka,David P. Tew,Florian Weigend +37 more
TL;DR: TURBOMOLE as mentioned in this paper is a software suite for large-scale quantum-chemical and materials science simulations of molecules, clusters, extended systems, and periodic solids.
References
More filters
Journal ArticleDOI
Generalized Gradient Approximation Made Simple
TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Journal ArticleDOI
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Journal ArticleDOI
Self-Consistent Equations Including Exchange and Correlation Effects
Walter Kohn,L. J. Sham +1 more
TL;DR: In this paper, the Hartree and Hartree-Fock equations are applied to a uniform electron gas, where the exchange and correlation portions of the chemical potential of the gas are used as additional effective potentials.
Journal ArticleDOI
Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
Journal ArticleDOI
Inhomogeneous Electron Gas
P. C. Hohenberg,Walter Kohn +1 more
TL;DR: In this article, the ground state of an interacting electron gas in an external potential was investigated and it was proved that there exists a universal functional of the density, called F[n(mathrm{r})], independent of the potential of the electron gas.