With the increasing interest in compounds containing heavier elements, experimental and theoretical community requires computationally efficient approaches capable of simultaneous non-perturbative treatment relativistic, spin-polarization, electron correlation effects. The ReSpect program has been designed with this goal mind developed to perform relativistic density functional theory (DFT) calculations on molecules solids at quasirelativistic two-component (X2C Hamiltonian) fully...

We report the first implementation of real-time time-dependent density functional theory (RT-TDDFT) at relativistic four-component level theory. In contrast to perturbative linear-response TDDFT approach (LR-TDDFT), RT-TDDFT performs an explicit time propagation Dirac-Kohn-Sham matrix, offering possibility simulate molecular spectroscopies involving strong electromagnetic fields while, same time, treating scalar and spin-orbit corrections variationally. The is based on matrix representation...

The solution of the Liouville-von Neumann equation in relativistic Dirac-Kohn-Sham density matrix formalism is presented and used to calculate X-ray absorption cross sections. Both dynamical relaxation effects spin-orbit corrections are included, as demonstrated by calculations SF6 near sulfur L2,3-edges. We also propose an analysis facilitating interpretation spectral transitions from real-time simulations, a selective perturbation that eliminates nonphysical excitations artifacts finite...

First principles theoretical modeling of out-of-equilibrium processes observed in attosecond pump-probe transient absorption spectroscopy (TAS) triggering pure electron dynamics remains a challenging task, especially for heavy elements and/or core excitations containing fingerprints scalar and spin-orbit relativistic effects. To address this, we formulate methodology simulating TAS within the real-time, time-dependent density functional theory (RT-TDDFT) framework, both valence energy...

The Liouville-von Neumann equation based on the four-component matrix Dirac-Kohn-Sham Hamiltonian is transformed to a quasirelativistic exact two-component (X2C) form and then used solve time evolution of electronic states only. By this means, significant acceleration by factor 7 or more has been achieved. transformation original motion formulated entirely in algebra, following closely X2C decoupling procedure Ilias Saue [ J. Chem. Phys. 2007 , 126 064102 ] proposed earlier for static...

A major challenge in computational solid-state physics is the capability of first-principles theories to treat relativistic effects nonperturbatively when modeling material properties driven by atomic-core regions or spin-orbit interaction. Such a approach mandatory for heavy-element containing materials that often exhibit nontrivial topological properties. Here, first formulation and implementation full-potential theory solids solving four-component Dirac-Kohn-Sham equation within local...

We present an implementation and application of electron dynamics based on real-time time-dependent density functional theory (RT-TDDFT) relativistic 2-component X2C 4-component Dirac–Coulomb (4c) Hamiltonians to the calculation circular dichroism optical rotatory dispersion spectra. In addition, resolution-of-identity approximation for Coulomb term (RI-J) is introduced into RT-TDDFT formulated entirely in terms complex quaternion algebra. The proposed methodology was assessed...

Two-dimensional (2D) materials exhibit a wide range of remarkable phenomena, many which owe their existence to the relativistic spin-orbit coupling (SOC) effects. To understand and predict properties containing heavy elements, such as transition-metal dichalcogenides (TMDs), effects must be taken into account in first-principles calculations. We present an all-electron method based on four-component Dirac Hamiltonian Gaussian-type orbitals (GTOs) that overcomes complications associated with...

We present a novel function fitting method for approximating the propagation of time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations absorption spectrum require discrete Fourier transforms moment. The spectral resolution is determined by total time, i.e., trajectory length moment, causing high computational cost. Our developed uses on shorter trajectories achieving arbitrary through extrapolation. Numerical testing shows that can...

We discuss the characteristic factors that determine electrochemical potentials in a metal-organic framework used as cathode for Li-ion batteries via density functional theory-based simulations. Our focus is on MIL-101(Fe) material. study gives insight into role of local atomic environment and structural deformations generating potential.

We discuss the applicability of naturally occurring compound Ferrous Oxalate Dihydrate (FOD) (FeC2O4·2H2O) as an anode material in Li-ion batteries. Using first-principles modeling, we evaluate electrochemical activity FOD and demonstrate how its structural water content affects intercalation reaction contributes to performance. show that both Li0 Li+ yields similar results. Our analysis indicates fully dehydrated ferrous oxalate is a more promising anodic with higher stability: it carries...

We present an all-electron, four-component relativistic implementation of electric field gradients (EFGs) at the nuclei using Gaussian-type orbitals and periodic boundary conditions. This allows us to include effects variationally, which is important for compounds containing heavy elements a property dependent electronic structure close nuclei. The all-electron approach ensures accurate treatment both core valence orbitals, as are in evaluation EFGs. Computational efficiency achieved through...

Two-dimensional (2D) materials exhibit a wide range of remarkable phenomena, many which owe their existence to the relativistic spin-orbit coupling (SOC) effects. To understand and predict properties containing heavy elements, such as transition-metal dichalcogenides (TMDs), effects must be taken into account in first-principles calculations. We present an all-electron method based on four-component Dirac Hamiltonian Gaussian-type orbitals (GTOs) that overcomes complications associated with...

We present a novel function fitting method for approximating the propagation of time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations absorption spectrum require discrete Fourier transforms moment. The spectral resolution is determined by total time, i.e. trajectory length moment, causing high computational cost. Our developed uses on shorter trajectories achieving arbitrary through extrapolation. Numerical testing shows that can...

Recent advances in laser technology enable to follow electronic motion at its natural time-scale with ultrafast pulses, leading the way towards atto- and femtosecond spectroscopic experiments of unprecedented resolution. Understanding these laser-driven processes, which almost inevitably involve non-linear light-matter interactions non-equilibrium electron dynamics, is challenging requires a common effort theory experiment. Real-time structure methods provide most straightforward simulate...

First principle theoretical modeling of out-of-equilibrium processes observed in attosecond pump-probe transient absorption spectroscopy (TAS) triggering pure electron dynamics remains a challenging task, specially for heavy elements and/or core excitations containing fingerprints scalar and spin-orbit relativistic effects. To address this, we formulate methodology simulating TAS within the real-time time-dependent density functional theory (RT-TDDFT) framework, both valence energy regime....