Results for “electronic structure theory” — Page 32

DOE OSTI2020

Molecular-Level Exploration of the Structure-Function Relations Underlying Interfacial Charge Transfer in the Subphthalocyanine/C 60 Organic Photovoltaic System

The arrangement of organic molecules at the donor-acceptor interface in an organic photovoltaic (OPV) cell can have a strong effect on the generation of charge carriers and thereby cell performance. In this paper, we report the molecular-level exploration of the ensemble of interfacial donor-acceptor pair geometries and the charge-transfer (CT) rates to which they give rise. Our approach combines molecular-dynamics simulations, electronic structure calculations, machine learning, and rate theory. This approach is applied to the boron subphthalocyanine chloride (donor) and C 60 (acceptor) OPV system. In this work we find that the interface is dominated by a previously unreported donor-acceptor pair edge geometry, which contributes significantly to device performance in a manner that depends on the initial conditions. Quantitative relations between the morphology and CT rates are established, which can be used to advance the design of more efficient OPV devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Valley-polarized nematic order in twisted moiré systems: In-plane orbital magnetism and crossover from non-Fermi liquid to Fermi liquid

Not Available

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Strong magnetic proximity effect in van der Waals heterostructures driven by direct hybridization

Not Available

36 MATERIALS SCIENCE↗

DOE OSTI2022

Dense plasma opacity via the multiple-scattering method

The calculation of the optical properties of hot dense plasmas with a model that has self-consistent plasma physics is a grand challenge for high energy density science. Here we exploit a recently developed electronic structure model that uses multiple scattering theory to solve the Kohn-Sham density functional theory equations for dense plasmas. Here we calculate opacities in this regime, validate the method, and apply it to recent experimental measurements of opacity for Cr, Ni, and Fe. Good agreement is found in the quasicontinuum region for Cr and Ni, while the self-consistent plasma physics of the approach cannot explain the observed difference between models and the experiment for Fe.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2020

Extreme Fermi Surface Smearing in a Maximally Disordered Concentrated Solid Solution

We show that the Fermi surface can survive the presence of extreme compositional disorder in the equiatomic alloy Ni 0.25 Fe 0.25 Co 0.25 Cr 0.25 . Our high-resolution Compton scattering experiments reveal a Fermi surface which is smeared across a significant fraction of the Brillouin zone (up to 40% of $\frac{2π}{a}$). The extent of this smearing and its variation on and between different sheets of the Fermi surface have been determined, and estimates of the electron mean free path and residual resistivity have been made by connecting this smearing with the coherence length of the quasiparticle states.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Electron Glass Phase with Resilient Zhang-Rice Singlets in LiCu 3 ⁢O 3

LiCu 3 ⁢O 3 is an antiferromagnetic mixed valence cuprate where trilayers of edge-sharing Cu(II)O (3⁢d 9 ) are sandwiched in between planes of Cu(I) (3⁢d 10 ) ions, with Li stochastically substituting Cu(II). Angle-resolved photoemission spectroscopy (ARPES) and density functional theory reveal two insulating electronic subsystems that are segregated in spite of sharing common oxygen atoms: a Cu d z 2 /O p z derived valence band (VB) dispersing on the Cu(I) plane, and a Cu 3⁢d x 2 -y 2 /O 2⁢p x,y derived Zhang-Rice singlet (ZRS) band dispersing on the Cu(II)O planes. First-principle analysis shows the Li substitution to stabilize the insulating ground state, but only if antiferromagnetic correlations are present. Li further induces substitutional disorder and a 2D electron glass behavior in charge transport, reflected in a large 530 meV Coulomb gap and a linear suppression of VB spectral weight at E F that is observed by ARPES. Surprisingly, the disorder leaves the Cu(II)-derived ZRS largely unaffected. Finally, this indicates a local segregation of Li and Cu atoms onto the two separate corner-sharing Cu⁡(II)⁢O 2 sub-lattices of the edge-sharing Cu(II)O planes, and highlights the ubiquitous resilience of the entangled two hole ZRS entity against impurity scattering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Charge trapping at Al/Al 2 ⁢O 3 interface facilitates hydrogen-induced superabundant metal vacancy formation

Hydrogen is a ubiquitous impurity that deteriorates the metal/oxide interface, causing challenges such as current leakage and blistering. Here, in this work, we uncover the mechanisms behind hydrogen-induced damage at the prototypical Al/A⁢l 2 ⁢O 3 interface. The precursor that we identify is charge trapping at the interface, which facilitates hydrogen segregation to the interface plane as H – . Presence of hydrogen increases aluminum vacancy concentration at the interfacial metal and oxide planes. Each Al vacancy can trap multiple hydrogen atoms. As a result, the interfacial aluminum vacancy and hydrogen concentrations increase by orders of magnitude. Additionally, hydrogen behaves as an n-type dopant and increases electronic conductivity at the oxide layer adjacent to the interface by forming H + , and the [V Al –H] complex is the predominant defect at this layer. These findings provide the precursor mechanisms of hydrogen-induced damage at the metal-oxide interfaces and have implications for advancing Al/A⁢l 2 ⁢O 3 –based coatings and electronic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Evidence for Dominant Phonon-Electron Scattering in Weyl Semimetal WP 2

Not Available

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2023

The Predictive Power of Exact Constraints and Appropriate Norms in Density Functional Theory

Ground-state Kohn-Sham density functional theory provides, in principle, the exact ground-state energy and electronic spin densities of real interacting electrons in a static external potential. In practice, the exact density functional for the exchange-correlation (xc) energy must be approximated in a computationally efficient way. About 20 mathematical properties of the exact xc functional are known. In this work, we review and discuss these known constraints on the xc energy and hole. By analyzing a sequence of increasingly sophisticated density functional approximations (DFAs), we argue that (a) the satisfaction of more exact constraints and appropriate norms makes a functional more predictive over the immense space of many-electron systems and (b) fitting to bonded systems yields an interpolative DFA that may not extrapolate well to systems unlike those in the fitting set. We discuss both how the class of well-described systems has grown along with constraint satisfaction and the possibilities for future functional development.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020