A5106426860- Advanced Chemical Physics Studies
- Machine Learning in Materials Science
- Catalytic Processes in Materials Science
- Quantum, superfluid, helium dynamics
- Physics of Superconductivity and Magnetism
- Spectroscopy and Quantum Chemical Studies
- Graphene research and applications
- Catalysis and Oxidation Reactions
- Semiconductor materials and devices
- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- Molecular Junctions and Nanostructures
- Inorganic Fluorides and Related Compounds
- nanoparticles nucleation surface interactions
- Electron and X-Ray Spectroscopy Techniques
- Advanced NMR Techniques and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Dots Synthesis And Properties
- ZnO doping and properties
- Topological Materials and Phenomena
- 2D Materials and Applications
- Tensor decomposition and applications
- Statistical Mechanics and Entropy
- Geochemistry and Geologic Mapping
- Advanced Condensed Matter Physics
TU Wien
2016-2025
London Centre for Nanotechnology
2022
Thomas Young Centre
2022
Max Planck Institute for the Structure and Dynamics of Matter
2022
Max Planck Institute for Solid State Research
2015-2021
University of Vienna
2007-2021
Technical University of Munich
2016-2017
Kobe University
2017
University of Illinois Urbana-Champaign
2017
Max Planck Society
2015
The band lineup, or alignment, of semiconductors is investigated via first-principles calculations based on density functional theory (DFT) and many-body perturbation (MBPT). Twenty-one including C, Si, Ge in the diamond structure, BN, AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, InSb, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe zinc-blende GaN ZnO wurtzite structure are considered view their fundamental technological importance. Band alignments determined using valence conduction offsets from...
The ionization potential is a fundamental key quantity with great relevance to diverse material properties. We find that state of the art methods based on density functional theory and simple diagrammatic approaches as commonly taken in $GW$ approximation predict potentials semiconductors insulators unsatisfactorily. Good agreement between experiment obtained only when diagrams resulting from antisymmetry many-electron wave function are into account via vertex corrections self-energy....
We show that the inclusion of second-order screened exchange to random phase approximation allows for an accurate description electronic correlation in atoms and solids clearly surpassing approximation, but not yet approaching chemical accuracy. From a fundamental point view, method is self-correlation free one-electron systems. practical approach yields energies atoms, as well jellium electron gas within few kcal/mol exact values, atomization typically 2-3 experiment, excellent lattice...
We present an implementation of the canonical formulation second-order Møller-Plesset (MP2) perturbation theory within projector-augmented-wave method under periodic boundary conditions using a plane wave basis set. To demonstrate accuracy our approach we show that result for atomization energy LiH molecule at Hartree-Fock+MP2 level is in excellent agreement with well converged Gaussian-type-orbital calculations. establish feasibility employing MP2 its form to systems are three dimensions...
We present ab initio calculations on the structural and electronic properties of narrow-gap lead chalcogenides $\mathrm{Pb}X$ ($X=\mathrm{S}$, Se, Te). Particular emphasis is put correct description their exceptional compared to III-V II-VI semiconductors, such as very small magnitude band gap, unusual order gaps within series $[{E}_{g}(\mathrm{Pb}\mathrm{S})>{E}_{g}(\mathrm{Pb}\mathrm{Te})>{E}_{g}(\mathrm{Pb}\mathrm{Se})]$, high effective charge-carrier masses. Within standard...
Results for the lattice constants, atomization energies, and band gaps of typical semiconductors insulators are presented Hartree–Fock second-order Møller–Plesset perturbation theory (MP2). We find that MP2 tends to undercorrelate weakly polarizable systems overcorrelates strongly systems. As a result, constants overestimated large gap underestimated small The volume dependence correlation energy on static dielectric screening properties discussed in detail. Moreover, relationship between...
The random-phase approximation to the ground state correlation energy (RPA) in combination with exact exchange (EX) has brought Kohn–Sham (KS) density functional theory one step closer towards a universal, 'general purpose first-principles method'. In an effort systematically assess influence of several contributions beyond RPA, this paper presents dissociation energies small molecules and solids, activation for hydrogen transfer non-hydrogen reactions, as well reaction number common test...
There has been considerable recent interest in density functionals incorporating random phase approximation (RPA) ground-state correlation. By virtue of its full nonlocality, RPA correlation is compatible with exact Hartree-Fock-type exchange and describes van der Waals interactions exceptionally well [B. G. Janesko et al., J. Chem. Phys. 130, 081105 (2009); 131, 034110 (2009)]. One caveat that contains one-electron self-interaction error, which leads to disturbingly large energies the...
Highly accurate results for the homogeneous electron gas (HEG) have only been achieved to date within a diffusion Monte Carlo (DMC) framework. Here, we introduce newly developed stochastic technique, Full Configuration Interaction Quantum (FCIQMC), which samples exact wavefunction expanded in plane wave Slater determinants. Despite introduction of basis set incompleteness error, obtain finite-basis energy is significantly, and variationally lower than any previously published work...
The adsorption of small alkane molecules in purely siliceous and protonated chabazite has been investigated at different levels theory: (i) density-functional (DFT) calculations with a gradient-corrected exchange-correlation functional; DFT using the Perdew-Burke-Ernzerhof (PBE) functional corrections for missing dispersion forces form C6/R6 pair potentials (ii) C6 parameters vdW radii determined by fitting accurate energies large molecular data base (PBE−d) or (iii) derived from “atoms...
We demonstrate that natural orbitals allow for reducing the computational cost of wave function based correlated calculations, especially atoms and molecules in a large box, when plane basis set under periodic boundary conditions is used. The employed are evaluated on level second-order Møller–Plesset perturbation theory (MP2), which requires effort scales as O(N5), where N measure system size. Moreover, we find simple approximation scaling to O(N4) yields similar reduction number virtual...
Wet carbon interfaces are ubiquitous in the natural world and exhibit anomalous properties, which could be exploited by emerging technologies. However, progress is limited lack of understanding at molecular level. Remarkably, even for most fundamental system (a single water molecule interacting with graphene), there no consensus on nature interaction. We tackle this performing an extensive set complementary state-of-the-art computer simulations some world's largest supercomputers. From...
Using the finite simulation-cell homogeneous electron gas (HEG) as a model, we investigate convergence of correlation energy to complete basis set (CBS) limit in methods utilising plane-wave wavefunction expansions. Simple analytic and numerical results from second-order M{\o}ller-Plesset theory (MP2) suggest 1/M decay basis-set incompleteness error where M is number plane waves used calculation, allowing for straightforward extrapolation CBS limit. As shall show, choice truncation when...
Modern electronic structure theories can predict and simulate a wealth of phenomena in surface science solid-state physics. In order to allow for direct comparison with experiment, such ab initio predictions have be made the thermodynamic limit, substantially increasing computational cost many-electron wave-function theories. Here, we present method that achieves limit results solids surfaces using "gold standard" coupled cluster ansatz quantum chemistry unprecedented efficiency. We study...
We investigate the accuracy of a number wave function based methods at heart quantum chemistry for metallic systems. Using Hartree-Fock as reference, perturbative (M\o{}ller-Plesset) and coupled cluster theories are used to study uniform electron gas model. Our findings suggest that nonperturbative acceptable modeling electronic interactions in metals while not. screened interactions, we propose simple modification widely singles doubles plus triples method lifts divergent behavior is shown...
We study a tensor hypercontraction decomposition of the Coulomb integrals periodic systems where are factorized into contraction six matrices which only two distinct. find that can be well approximated in this form already with small compared to number real space grid points. The cost computing scales as O(N4) using regularized alternating least squares algorithm. studied factorization exploited reduce scaling computational expensive contractions appearing amplitude equations coupled cluster...
In recent years, solid-state spin systems have emerged as promising candidates for quantum information processing (QIP). Prominent examples are the Nitrogen-Vacancy (NV) center in diamond, phosphorous dopants silicon (Si:P), rare-earth ions solids and V$_{\text{Si}}$-centers Silicon-carbide (SiC). The Si:P system has demonstrated, that by eliminating electron of dopant, its nuclear spins can yield exceedingly long coherence times. For NV centers, however, a proper charge state storage qubit...
In this work, we present a model of the surface states nonsymmorphic semimetals. These are derived from mass terms that lift high degeneracy imposed in band structure by bulk symmetries. Reflecting reduced symmetry at surface, bands strongly modified. This leads to creation two-dimensional floating bands, which distinct Shockley states, quantum well or topologically protected states. We focus on layered semimetal ZrSiS clarify origin its demonstrate an excellent agreement between DFT...
We present a method to correct for finite size errors in coupled cluster theory calculations of solids. The outlined technique shares similarities with electronic structure factor interpolation methods used quantum Monte Carlo calculations. However, our approach does not require the calculation density matrices. Furthermore we show that proposed corrections achieve chemical accuracy convergence second-order Møller-Plesset perturbation and singles doubles correlation energies per atom...
The explicitly correlated approach is one of the most important breakthroughs in ab initio electronic structure theory, providing arguably compact, accurate, and efficient ansatz for describing motion electrons. Since Hylleraas first used an wave function He atom 1929, numerous attempts have been made to tackle significant challenges involved constructing practical methods that are applicable larger systems. These include identifying suitable mathematical forms a evaluation many-electron...
We present a simple, robust, and black-box approach to the implementation use of local, periodic, atom-centered Gaussian basis functions within plane wave code, in computationally efficient manner. The procedure outlined is based on representation Gaussians finite bandwidth by their underlying coefficients. core region handled projected augment framework, pseudizing cutoff radius around each nucleus, smoothing so that they are faithfully represented with only moderate kinetic energy cutoff....
The adsorption energy of a molecule onto the surface material underpins wide array applications, spanning heterogeneous catalysis, gas storage, and many more. It is key quantity where experimental measurements theoretical calculations meet, with agreement being necessary for reliable predictions chemical reaction rates mechanisms. prototypical molecule–surface system CO adsorbed on MgO, but despite intense scrutiny from theory experiment, there still no consensus its energy. In particular,...
Coupled-cluster theories can be used to compute ab initio electronic correlation energies of real materials with systematically improvable accuracy. However, the widely coupled cluster singles and doubles plus perturbative triples [CCSD(T)] method is only applicable insulating materials. For zero-gap truncation underlying many-body perturbation expansion leads an infrared catastrophe. Here, we present a novel formalism denoted as (cT) that yields convergent in metallic systems. Furthermore,...