Publications related to Degenerate energy levels

Absolute energy levels of liquid water from many-body perturbation theory with effective vertex corrections

Alfredo Pasquarello, Thomas Bischoff, Aleksei Tal

We demonstrate the importance of addressing the F vertex and thus going beyond the GW approximation for achieving the energy levels of liquid water in manybody perturbation theory. In particular, we consider an effective vertex function in both the polariz ...

National Academy of Sciences2024

Hierarchy of quasisymmetries and degeneracies in the CoSi family of chiral crystal materials

Philip Johannes Walter Moll, Chunyu Guo, Yi-Chiang Sun

In materials, certain approximated symmetry operations can exist in a lower-order approximation of the effective model but are good enough to influence the physical responses of the system, and these approximated symmetries were recently dubbed "quasisymme ...

AMER PHYSICAL SOC2023

Emergence of Classical Magnetic Order from Anderson Towers: Quantum Darwinism in Action

Frédéric Mila

Environment is assumed to play a negative role in quantum mechanics, destroying the coherence in a quantum system and, thus, randomly changing its state. However, for a quantum system that is initially in a degenerate ground state, the situation could be d ...

American Physical Society2023

Machine-learning the electronic density of states: electronic properties without quantum mechanics

Chiheb Ben Mahmoud

The electronic density of states (DOS) quantifies the distribution of the energy levels that can be occupied by electrons in a quasiparticle picture and is central to modern electronic structure theory. It also underpins the computation and interpretation ...

EPFL2023

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Chao Wang, Guang-Yu Sun, Haoxiang Zhao

High-voltage and high-power devices are indispensablein spacecraftfor outer space explorations, whose operations require aerospace materialswith adequate vacuum surface insulation performance. Despite persistentattempts to fabricate such materials, current ...

AMER CHEMICAL SOC2023

Bending and Stretching in a Narrow Ribbon of Nematic Polymer Networks

Harmeet Singh

We study the spontaneous out-of-plane bending of a planar untwisted ribbon composed of nematic polymer networks activated by a change in temperature. Our theory accounts for both stretching and bending energies, which compete to establish equilibrium. We s ...

SPRINGER2023

Emergent non-Hermitian localization phenomena in the synthetic space of zero-dimensional bosonic systems

Fabrizio Minganti

Phase transitions in non-Hermitian systems are at the focus of cutting edge theoretical and experimental research. On the one hand, parity-time- (PT-) and anti-PT-symmetric physics have gained ever-growing interest, due to the existence of non-Hermitian sp ...

AMER PHYSICAL SOC2023

Interface connection of functionalized carbon nanotubes for efficient and stable perovskite solar cells

Mohammad Khaja Nazeeruddin, Jianxing Xia, Ruiyuan Hu

The ionic defects of hetero-junction interfaces always attract and trap carriers via surface electrostatic forces, which are crucial for the efficiency and intrinsic stability of perovskite solar cells (PSCs). Herein, functionalized carbon nanotubes (CNTs) ...

Royal Society of Chemistry2023

Rapid transformation of wildfire emissions to harmful background aerosol

Athanasios Nenes, Spyros Pandis

Wildfires are a significant source of organic aerosol during summer, with major impacts on air quality and climate. However, studies in Europe suggest a surprisingly low (less than 10%) contribution of biomass burning organic aerosol to average summertime ...

Nature Portfolio2023

Development of a reduced model for energetic particle transport by sawteeth in tokamaks

Mario Ludovico Podesta, Francesca Maria Poli, Anna Teplukhina, Matteo Vallar, Jiangyan Yang

The sawtooth instability is known for inducing transport and loss of energetic particles (EPs), and for generating seed magnetic islands that can trigger tearing modes. Both effects degrade the overall plasma performance. Several theories and numerical mod ...

2022

Spin Evolution in the Born-Oppenheimer Approximation

Jean-Philippe Ansermet, François Reuse, Klaus Maschke

The first part of this article attempts to highlight in chronological order some prominent papers that have direct connexion with the Born-Oppenheimer approximation. This timeline successively points to the role of level crossing, the notions of gauge fiel ...

WILEY-V C H VERLAG GMBH2022

Quantum Circuits for the Preparation of Spin Eigenfunctions on Quantum Computers

Alessandro Carbone

The application of quantum algorithms to the study of many-particle quantum systems requires the ability to prepare wave functions that are relevant in the behavior of the system under study. Hamiltonian symmetries are important instruments used to classif ...

MDPI2022

One-Shot Approach for Enforcing Piecewise Linearity on Hybrid Functionals: Application to Band Gap Predictions

Alfredo Pasquarello, Stefano Falletta, Jing Yang

We present an efficient procedure for constructing nonempirical hybrid functionals to accurately predict band gaps of extended systems. We determine mixing parameters by enforcing the generalized Koopmans’ condition on localized electron states, which are ...

2022

Landau levels of the Euler class topology

Oleg Yazyev, Yifei Guan

Two-dimensional systems with C2T (PT) symmetry exhibit the Euler class topology E is an element of Z in each two-band subspace realizing a fragile topology beyond the symmetry indicators. By systematically studying the energy levels of Euler insulating pha ...

AMER PHYSICAL SOC2022

Tensor network investigation of frustrated Ising models

Jeanne Colbois

In spin systems, geometrical frustration describes the impossibility of minimizing simultaneously all the interactions in a Hamiltonian, often giving rise to macroscopic ground-state degeneracies and emergent low-temperature physics. In this thesis, combin ...

EPFL2022

Robust Interfacial Modifier for Efficient Perovskite Solar Cells: Reconstruction of Energy Alignment at Buried Interface by Self-Diffusion of Dopants

Mohammad Khaja Nazeeruddin, Jianxing Xia

The under-coordinated defects within perovskite and its relevant interfaces always attract and trap the free carriers via the electrostatic force, significantly limiting the charge extraction efficiency and the intrinsic stability of perovskite solar cells ...

WILEY-V C H VERLAG GMBH2022

Revealing higher-order light and matter energy exchanges using quantum trajectories in ultrastrong coupling

Fabrizio Minganti

The dynamics of open quantum systems is often modeled using master equations, which describe the expected outcome of an experiment (i.e., the average over many realizations of the same dynamics). Quantum trajectories, instead, model the outcome of ideal si ...

AMER PHYSICAL SOC2022

Deep defects in InGaN LEDs: modeling the impact on the electrical characteristics

Nicolas Grandjean, Jean-François Carlin, Camille Haller

Deep defects have a fundamental role in determining the electro-optical characteristics and in the efficiency of InGaN light-emitting diodes (LEDs). However, modeling their effect on the electrical characteristics of the LED is not straightforward. ...

SPIE-INT SOC OPTICAL ENGINEERING2022

Magnetic Properties of Surface Adsorbed Metal Adatoms and Dimers

Dante Philippe Sblendorio

This thesis investigates the magnetic properties of single atoms and dimers adsorbed on graphene and oxide decoupling layers supported by single crystal metal substrates, using scanning tunneling microscopy (STM) and spin-polarized scanning tunneling micro ...

EPFL2022

A global line list for HDO between 0 and 35000 cm−1 constructed using multiphoton spectra

Oleg Boyarkine

Multiphoton spectroscopy of monodeuterated water is employed to determine more than 210 new energy levels of HDO in the 25 000–35 000 cm region. These new empirical energy levels are used to fit a potential energy surface (PES) valid between 20 000 cm and ...

2021