Relativistic Orbital Optimized Density Functional Theory for Accurate Core-Level Spectroscopy

Abstract

Core-level spectra of 1s electrons of elements heavier than Ne show significant relativistic effects. We combine advances in orbital optimized DFT (OO-DFT) with the spin-free exact two-component (X2C) model for scalar relativistic effects, to study K-edge spectra of third period elements. OO-DFT/X2C is found to be quite accurate at predicting energies, yielding $\sim 0.5$ eV RMS error vs experiment with the modern SCAN (and related) functionals. This marks a significant improvement over the $>50$ eV deviations that are typical for the popular time-dependent DFT (TDDFT) approach. Consequently, experimental spectra are quite well reproduced by OO-DFT/X2C, sans empirical shifts for alignment. OO-DFT/X2C combines high accuracy with ground state DFT cost and is thus a promising route for computing core-level spectra of third period elements. We also explored K and L edges of 3d transition metals to identify limitations of the OO-DFT/X2C approach in modeling the spectra of heavier atoms.

References in corpus (15)

• Climbing the Density Functional Ladder: Non-Empirical Meta-Generalized Gradient Approximation Designed for Molecules and Solids
• Recent developments in the PySCF program package
• Orbital Optimized Density Functional Theory for Electronic Excited States
• Excited state orbital optimization via minimizing the square of the gradient: General approach and application to singly and doubly excited states via density functional theory
• SCAN-based hybrid and double-hybrid density functionals from models without fitted parameters
• Highly Accurate Prediction of Core Spectra of Molecules at Density Functional Theory Cost: Attaining sub eV Error from a Restricted Open-Shell Kohn-Sham Approach
• Delocalization errors in density functional theory are essentially quadratic in fractional occupation number
• Variational density functional calculations of excited states via direct optimization
• $\sigma$-SCF: A Direct Energy-targeting Method To Mean-field Excited States
• Accurate absolute core-electron binding energies of molecules, solids and surfaces from first-principles calculations
• Relativistic EOM-CCSD for core-excited and core-ionized state energies based on the 4-component Dirac-Coulomb(-Gaunt) Hamiltonian
• Accurate prediction of core-level spectra of radicals at density functional theory cost via square gradient minimization and recoupling of mixed configurations
• An analysis of the performance of coupled cluster methods for core excitations and core ionizations using standard basis sets
• Beyond the electric-dipole approximation in simulations of X-ray absorption spectroscopy: Lessons from relativistic theory
• Core Excitations with Excited State Mean Field and Perturbation Theory

Cited by in corpus (12)

• Density Functional Theory for Electronic Excited States
• Femtosecond Symmetry Breaking and Coherent Relaxation of Methane Cations at the Carbon K-Edge
• Electron-Affinity Time-Dependent Density Functional Theory: Formalism and Applications to Core-Excited States
• Accurate core excitation and ionization energies from a state-specific coupled-cluster singles and doubles approach
• State-Specific Coupled-Cluster Methods for Excited States
• Computing X-ray absorption spectra from linear-response particles atop optimized holes
• Towards accurate spin-orbit splittings from relativistic multireference electronic structure theory
• Generalization of one-center non orthogonal configuration interaction singles to open shell singlet reference states: Theory and application to valence-core pump-probe states in acetylacetone
• Double Configuration Interaction Singles: Scalable and size-intensive approach for orbital relaxation in excited states and bond-dissociation
• Measurement of Coherent Vibrational Dynamics with X-ray Transient Absorption Spectroscopy Simultaneously at the Carbon K- and Chlorine L${}_{2,3}$- Edges
• Attosecond Probing of Coherent Vibrational Dynamics in CBr${}_4$
• Single-particle-exact density functional theory