arXiv subjects

Dorothea Golze

Publications and source records attributed to Dorothea Golze.

At least 19 recordsLinked to original sources

arXiv2026

Roadmap on Advancements of the FHI-aims Software Package

Electronic-structure theory is the foundation of the description of materials including multiscale modeling of their properties and functions. Obviously, without sufficient accuracy at the base, reliable predictions are unlikely at any level that follows. The software package FHI-aims has proven to be a game changer for accurate free-energy calculations because of its scalability, numerical precision, and its efficient handling of density functional theory (DFT) with hybrid functionals and van der Waals interactions. It treats molecules, clusters, and extended systems (solids and liquids) on an equal footing. Besides DFT, FHI-aims also includes quantum-chemistry methods, descriptions for excited states and vibrations, and calculations of various types of transport. Recent advancements address the integration of FHI-aims into an increasing number of workflows and various artificial intelligence (AI) methods. This Roadmap describes the state-of-the-art of FHI-aims and advancements that are currently ongoing or planned.

cond-mat.mtrl-sci↗

arXiv2025

Decoding Shake-up Satellites in XPS through Large-Scale ab initio Simulations: Spectral Signatures of Ring Fusion in Porphyrins

In X-ray photoelectron spectroscopy (XPS), shake-up satellites arise when core ionization is accompanied by simultaneous charge-neutral valence excitations. Although these satellites can contain detailed structural information, they are rarely interpreted due to the lack of accurate and scalable theoretical methods. Here, we develop and apply a many-body perturbation theory framework within the $GW$ plus cumulant ($GW+C$) approach that enables accurate predictions of shake-up satellites in large molecular systems. For unfused, mono-fused, and doubly fused porphyrin derivatives with up to 170 atoms, we achieve excellent agreement with experiment, reproducing both main photoionization signals and satellite features within $0.2-0.3$ eV. We show that ring fusion strongly affects satellite features, whereas the N 1s photoionization signals remain unchanged. Our calculations reveal the mechanism behind these changes, identifying the spatial localization of valence excitations as the driving force. This work not only deepens understanding of the shake-up mechanism in porphyrins but also shows how predictive computations can unlock the chemical information encoded in satellites.

physics.chem-ph↗

arXiv2025

The CP2K Program Package Made Simple

CP2K is a versatile open-source software package for simulations across a wide range of atomistic systems, from isolated molecules in the gas phase to low-dimensional functional materials and interfaces, as well as highly symmetric crystalline solids, disordered amorphous glasses, and weakly interacting soft-matter systems in the liquid state and in solution. This review highlights CP2K's capabilities for computing both static and dynamical properties using quantum-mechanical and classical simulation methods. In contrast to the accompanying theory and code paper [J. Chem. Phys. 152, 194103 (2020)], the focus here is on the practical usage and applications of CP2K, with underlying theoretical concepts introduced only as needed.

physics.comp-ph↗

arXiv2024

GW plus cumulant approach for predicting core-level shake-up satellites in large molecules

Recently, the $GW$ approach has emerged as a valuable tool for computing deep core-level binding energies as measured in X-ray photoemission spectroscopy. However, $GW$ fails to accurately predict shake-up satellite features, which arise from charge-neutral excitations accompanying the ionization. In this work, we extend the $GW$ plus cumulant ($GW+C$) approach to molecular 1s excitations, deriving conditions under which $GW+C$ can be reliably applied to shake-up processes. We present an efficient implementation with $O(N^4)$ scaling with respect to the system size $N$, within an all-electron framework based on numeric atom-centered orbitals. We demonstrate that decoupling the core and valence spaces is crucial when using localized basis functions. Additionally, we meticulously validate the basis set convergence of the satellite spectrum for 65 spectral functions and identify the importance of diffuse augmenting functions. To assess the accuracy, we apply our $GW+C$ scheme to $π$-conjugated molecules containing up to 40 atoms, predicting dominant satellite features within 0.5~eV of experimental values. For the acene series, from benzene to pentacene, we demonstrate how $GW+C$ provides critical insights into the interpretation of experimentally observed satellite features.

physics.chem-ph↗

arXiv2024

Precision benchmarks for solids: G0W0 calculations with different basis sets

The GW approximation within many-body perturbation theory is the state of the art for computing quasiparticle energies in solids. Typically, Kohn-Sham (KS) eigenvalues and eigenfunctions, obtained from a Density Functional Theory (DFT) calculation are used as a starting point to build the Green's function G and the screened Coulomb interaction W, yielding the one-shot G0W0 selfenergy if no further update of these quantities are made. Multiple implementations exist for both the DFT and the subsequent G0W0 calculation, leading to possible differences in quasiparticle energies. In the present work, the G0W0 quasiparticle energies for states close to the band gap are calculated for six crystalline solids, using four different codes: Abinit, exciting, FHI-aims, and GPAW. This comparison helps to assess the impact of basis-set types (planewaves versus localized orbitals) and the treatment of core and valence electrons (all-electron full potentials versus pseudopotentials). The impact of unoccupied states as well as the algorithms for solving the quasiparticle equation are also briefly discussed. For the KS-DFT band gaps, we observe good agreement between all codes, with differences not exceeding 0.1 eV, while the G0W0 results deviate on the order of 0.1-0.3 eV. Between all-electron codes (FHI-aims and exciting), the agreement is better than 15 meV for KS-DFT and, with one exception, about 0.1 eV for G0W0 band gaps.

cond-mat.mtrl-sci↗

arXiv2024

Solving multi-pole challenges in the GW100 benchmark enables precise low-scaling GW calculations

The $GW$ approximation is a widely used method for computing electron addition and removal energies of molecules and solids. The computational effort of conventional $GW$ algorithms increases as $O(N^4)$ with the system size $N$, hindering the application of $GW$ to large and complex systems. Low-scaling $GW$ algorithms are currently very actively developed. Benchmark studies at the single-shot $G_0W_0$ level indicate excellent numerical precision for frontier quasiparticle energies, with mean absolute deviations $<10$ meV between low-scaling and standard implementations for the widely used $GW100$ test set. A notable challenge for low-scaling $GW$ algorithms remains in achieving high precision for five molecules within the $GW100$ test set, namely O$_3$, BeO, MgO, BN, and CuCN, for which the deviations are in the range of several hundred meV at the $G_0W_0$ level. This is due to a spurious transfer of spectral weight from the quasiparticle to the satellite spectrum in $G_0W_0$ calculations, resulting in multi-pole features in the self-energy and spectral function, which low-scaling algorithms fail to describe. We show in this work that including eigenvalue self-consistency in the Green's function ($\text{ev}GW_0$) achieves a proper separation between satellite and quasiparticle peak, leading to a single solution of the quasiparticle equation with spectral weight close to one. $\text{ev}GW_0$ quasiparticles energies from low-scaling $GW$ closely align with reference calculations; the mean absolute error is only 12 meV for the five molecules. We thus demonstrate that low-scaling $GW$ with self-consistency in $G$ is well-suited for computing frontier quasiparticle energies.

physics.chem-ph↗

arXiv2024

Electronic Structure and Topology in Gulf-edged Zigzag Graphene Nanoribbons

With advanced synthetic techniques, a wide variety of well-defined graphene nano-ribbons (GNRs) can be produced with atomic precision. Hence, finding the relation between their structures and properties becomes important for the rational design of GNRs. In this work, we explore the complete chemical space of gulf-edged zigzag graphene nanoribbons (ZGNR-Gs), a subclass of zigzag GNRs in which the zigzag edges miss carbon atoms in a regular sequence. We demonstrate that the electronic properties of ZGNR-Gs depend on four structural parameters: ribbon width, gulf edge size, unit length, and gulf offset. Using tight-binding calculations and the Hubbard model, we find that all ZGNR-Gs are semiconductors with varying band gaps; there are no metals in this class of materials. Notably, when spin polarization is considered, most ZGNR-Gs exhibit antiferromagnetic behavior, with the spin moments and spin-induced band gap opening being stabilized by longer zigzag segments at the edges. Furthermore, we provide simple empirical rules that describe the Z2 topological invariant based on the aforementioned structural parameters. By analyzing the full chemical space of ZGNR-Gs, we offer insights into the design of GNRs with desired electronic, magnetic, and topological properties for nanoelectronic applications.

cond-mat.mtrl-sci↗

arXiv2024

Validation of the GreenX library time-frequency component for efficient GW and RPA calculations

Electronic structure calculations based on many-body perturbation theory (e.g. GW or the random-phase approximation (RPA)) require function evaluations in the complex time and frequency domain, for example inhomogeneous Fourier transforms or analytic continuation from the imaginary axis to the real axis. For inhomogeneous Fourier transforms, the time-frequency component of the GreenX library provides time-frequency grids that can be utilized in low-scaling RPA and GW implementations. In addition, the adoption of the compact frequency grids provided by our library also reduces the computational overhead in RPA implementations with conventional scaling. In this work, we present low-scaling GW and conventional RPA benchmark calculations using the GreenX grids with different codes (FHI-aims, CP2K and ABINIT) for molecules, two-dimensional materials and solids. Very small integration errors are observed when using 30 time-frequency points for our test cases, namely $<10^{-8}$ eV/electron for the RPA correlation energies, and 10 meV for the GW quasiparticle energies.

physics.comp-ph↗

arXiv2024

Benchmarking the accuracy of the separable resolution of the identity approach for correlated methods in the numeric atom-centered orbitals framework

Four-center two-electron Coulomb integrals routinely appear in electronic structure algorithms. The resolution-of-the-identity (RI) is a popular technique to reduce the computational cost for the numerical evaluation of these integrals in localized basis-sets codes. Recently, Duchemin and Blase proposed a separable RI scheme [J. Chem. Phys. 150, 174120 (2019)], which preserves the accuracy of the standard global RI method with the Coulomb metric (RI-V) and permits the formulation of cubic-scaling random phase approximation (RPA) and $GW$ approaches. Here, we present the implementation of a separable RI scheme within an all-electron numeric atom-centered orbital framework. We present comprehensive benchmark results using the Thiel and the GW100 test set. Our benchmarks include atomization energies from Hartree-Fock, second-order Møller-Plesset (MP2), coupled-cluster singles and doubles, RPA and renormalized second-order perturbation theory as well as quasiparticle energies from $GW$. We found that the separable RI approach reproduces RI-free HF calculations within 9 meV and MP2 calculations within 1 meV. We have confirmed that the separable RI error is independent of the system size by including disordered carbon clusters up to 116 atoms in our benchmarks

physics.chem-ph↗

arXiv2023

Accelerating core-level $GW$ calculations by combining the contour deformation approach with the analytic continuation of $W$

In recent years, the $GW$ method has emerged as a reliable tool for computing core-level binding energies. The contour deformation (CD) technique has been established as an efficient, scalable, and numerically stable approach to compute the $GW$ self-energy for deep core excitations. However, core-level $GW$ calculations with CD face the challenge of higher scaling with respect to system size $N$ compared to the conventional quartic scaling in valence state algorithms. In this work, we present the CD-WAC method (CD with $W$ Analytic Continuation), which reduces the scaling of CD applied to the inner shells from $O(N^5)$ to $O(N^4)$ by employing an analytic continuation of the screened Coulomb interaction $W$. Our proposed method retains the numerical accuracy of CD for the computationally challenging deep core case, yielding mean absolute errors $<5$ meV for well-established benchmark sets, such as CORE65, for single-shot $GW$ calculations. More extensive testing for different $GW$ flavors prove the reliability of the method. We have confirmed the theoretical scaling by performing scaling experiments on large acene chains and amorphous carbon clusters, achieving speedups of up to 10x for structures of only 116 atoms. This improvement in computational efficiency paves the way for more accurate and efficient core-level $GW$ calculations on larger and more complex systems.

physics.comp-ph↗

arXiv2022

Combining Renormalized Singles $GW$ Methods with the Bethe-Salpeter Equation for Accurate Neutral Excitation Energies

We apply the renormalized singles (RS) Green's function in the Bethe-Salpeter equation (BSE)/$GW$ approach to predict accurate neutral excitation energies of molecular systems. The BSE calculations are performed on top of the $G_{\text{RS}}W_{\text{RS}}$ method, which uses the RS Green's function also for the computation of the screened Coulomb interaction $W$. We show that the BSE/$G_{\text{RS}}W_{\text{RS}}$ approach significantly outperforms BSE/$G_0W_0$ for predicting excitation energies of valence, Rydberg and charge transfer (CT) excitations by benchmarking the Truhlar-Gagliardi set, Stein CT set and an atomic Rydberg test set. For the Truhlar-Gagliardi test set, BSE/$G_{\text{RS}}W_{\text{RS}}$ provides comparable accuracy to time-dependent density functional theory (TDDFT) and is slightly better than BSE starting from eigenvalue self-consistent $GW$ (ev$GW$). For the Stein CT test set, BSE/$G_{\text{RS}}W_{\text{RS}}$ significantly outperforms BSE/$G_0W_0$ and TDDFT with the accuracy comparable to BSE/ev$GW$. We also show that BSE/$G_{\text{RS}}W_{\text{RS}}$ predicts Rydberg excitation energies of atomic systems well. Besides the excellent accuracy, BSE/$G_{\text{RS}}W_{\text{RS}}$ largely eliminates the dependence on the choice of the density functional approximation. This work demonstrates that the BSE/$G_{\text{RS}}W_{\text{RS}}$ approach is accurate and efficient for predicting excitation energies for a broad range of systems, which expands the applicability of the BSE/$GW$ approach.

physics.chem-ph↗

arXiv2022

Accurate computational prediction of core-electron binding energies in carbon-based materials: A machine-learning model combining density-functional theory and $\boldsymbol{GW}$

We present a quantitatively accurate machine-learning (ML) model for the computational prediction of core-electron binding energies, from which x-ray photoelectron spectroscopy (XPS) spectra can be readily obtained. Our model combines density functional theory (DFT) with $GW$ and uses kernel ridge regression for the ML predictions. We apply the new approach to materials and molecules containing carbon, hydrogen and oxygen, and obtain qualitative and quantitative agreement with experiment, resolving spectral features within 0.1 eV of reference experimental spectra. The method only requires the user to provide a structural model for the material under study to obtain an XPS prediction within seconds. Our new tool is freely available online through the XPS Prediction Server.

cond-mat.mtrl-sci↗

arXiv2022

Benchmark of $\boldsymbol{GW}$ Methods for Core-Level Binding Energies

The $GW$ approximation has recently gained increasing attention as a viable method for the computation of deep core-level binding energies as measured by X-ray photoelectron spectroscopy (XPS). We present a comprehensive benchmark study of different $GW$ methodologies (starting-point optimized, partial and full eigenvalue-self-consistent, Hedin shift and renormalized singles) for molecular inner-shell excitations. We demonstrate that all methods yield a unique solution and apply them to the CORE65 benchmark set and ethyl trifluoroacetate. Three $GW$ schemes clearly outperform the other methods for absolute core-level energies with a mean absolute error of 0.3 eV with respect to experiment. These are partial eigenvalue self-consistency, in which the eigenvalues are only updated in the Green's function, single-shot $GW$ calculations based on an optimized hybrid functional starting point and a Hedin shift in the Green's function. While all methods reproduce the experimental relative binding energies well, the eigenvalue self-consistent schemes and the Hedin shift yield with mean errors $<0.2$ eV the best results.

physics.chem-ph↗

arXiv2021

Towards GW Calculations on Thousands of Atoms

The GW approximation of many-body perturbation theory is an accurate method for computing electron addition and removal energies of molecules and solids. In a canonical implementation, however, its computational cost is $O(N^4)$ in the system size N, which prohibits its application to many systems of interest. We present a full-frequency GW algorithm in a Gaussian type basis, whose computational cost scales with $N^2$ to $N^3$. The implementation is optimized for massively parallel execution on state-of-the-art supercomputers and is suitable for nanostructures and molecules in the gas, liquid or condensed phase, using either pseudopotentials or all electrons. We validate the accuracy of the algorithm on the GW100 molecular test set, finding mean absolute deviations of 35 meV for ionization potentials and 27 meV for electron affinities. Furthermore, we study the length-dependence of quasiparticle energies in armchair graphene nanoribbons of up to 1734 atoms in size, and compute the local density of states across a nanoscale heterojunction.

physics.chem-ph↗

arXiv2021

Low-scaling $GW$ with benchmark accuracy and application to phosphorene nanosheets

$GW$ is an accurate method for computing electron addition and removal energies of molecules and solids. In a conventional $GW$ implementation, however, its computational cost is $O(N^4)$ in the system size $N$, which prohibits its application to many systems of interest. We present a low-scaling $GW$ algorithm with notably improved accuracy compared to our previous algorithm [J. Phys. Chem. Lett. 2018, 9, 306-312]. This is demonstrated for frontier orbitals using the $GW100$ benchmark set, for which our algorithm yields a mean absolute deviation of only 6 meV with respect to canonical implementations. We show that also excitations of deep valence, semi-core and unbound states match conventional schemes within 0.1 eV. The high accuracy is achieved by using minimax grids with 30 grid points and the resolution of the identity with the truncated Coulomb metric. We apply the low-scaling $GW$ algorithm with improved accuracy to phosphorene nanosheets of increasing size. We find that their fundamental gap is strongly size-dependent varying from 4.0 eV (1.8 nm $\times$ 1.3 nm, 88 atoms) to 2.4 eV (6.9 nm $\times$ 4.8 nm, 990 atoms) at the $\text{ev}GW_0$@PBE level.

physics.chem-ph↗

arXiv2020

Relativistic correction scheme for core-level binding energies from $GW$

We present a relativistic correction scheme to improve the accuracy of 1s core-level binding energies calculated from Green's function theory in the $GW$ approximation, which does not add computational overhead. An element-specific corrective term is derived as the difference between the 1s eigenvalues obtained from the self-consistent solutions to the non- or scalar-relativistic Kohn-Sham equations and the four-component Dirac-Kohn-Sham equations for a free neutral atom. We examine the dependence of this corrective term on the molecular environment and on the amount of exact exchange in hybrid exchange-correlation functionals. This corrective term is then added as a perturbation to the quasiparticle energies from partially self-consistent and single-shot $GW$ calculations. We show that this element-specific relativistic correction, when applied to a previously reported benchmark set of 65 core-state excitations [J. Phys. Chem. Lett. 11, 1840 (2020)], reduces the mean absolute error (MAE) with respect to experiment from 0.55 to 0.30 eV and eliminates the species dependence of the MAE, which otherwise increases with the atomic number. The relativistic corrections also reduce the species dependence for the optimal amount of exact exchange in the hybrid functional used as starting point for the single-shot $G_0W_0$ calculations. Our correction scheme can be transferred to other methods, which we demonstrate for the Delta self-consistent field ($Δ$SCF) approach based on density functional theory.

physics.chem-ph↗

arXiv2020

From flat to tilted: gradual interfaces in organic thin film growth

We investigate domain formation and local morphology of thin films of $α$-sexithiophene ($α$-6T) on Au(100) beyond monolayer coverage by combining high resolution scanning tunneling microscopy (STM) experiments with electronic structure theory calculations and computational structure search. We report a layerwise growth of highly-ordered enantiopure domains. For the second and third layer, we show that the molecular orbitals of individual $α$-6T molecules can be well resolved by STM, providing access to detailed information on the molecular orientation. We find that already in the second layer the molecules abandon the flat adsorption structure of the monolayer and adopt a tilted conformation. Although the observed tilted arrangement resembles the orientation of $α$-6T in the bulk, the observed morphology does not yet correspond to a well-defined surface of the $α$-6T bulk structure. A similar behavior is found for the third layer indicating a growth mechanism where the bulk structure is gradually adopted over several layers.

cond-mat.mtrl-sci↗

arXiv2020

CP2K: An Electronic Structure and Molecular Dynamics Software Package -- Quickstep: Efficient and Accurate Electronic Structure Calculations

CP2K is an open source electronic structure and molecular dynamics software package to perform atomistic simulations of solid-state, liquid, molecular and biological systems. It is especially aimed at massively-parallel and linear-scaling electronic structure methods and state-of-the-art ab-initio molecular dynamics simulations. Excellent performance for electronic structure calculations is achieved using novel algorithms implemented for modern high-performance computing systems. This review revisits the main capabilities of CP2k to perform efficient and accurate electronic structure simulations. The emphasis is put on density functional theory and multiple post-Hartree-Fock methods using the Gaussian and plane wave approach and its augmented all-electron extension.

physics.chem-ph↗