Delocalization of Quasiparticle Moiré States in Twisted Bilayer hBN.

Twisted bilayers host many emergent phenomena in which the electronic excitations (quasiparticles, QPs) are closely intertwined with the local stacking order. By inspecting twisted hexagonal boron nitride (t-hBN), we show that nonlocal long-range interactions in large twisted systems cannot be reliably described by the local (high-symmetry) stacking and that the band gap variation (typically associated with the moiré excitonic potential) shows multiple minima with variable depth depending on the twist angle. We investigate twist angles of 2.45°, 2.88°, 3.48°, and 5.09° using the GW approximation together with stochastic compression to analyze the QP state interactions. We find that band-edge QP hybridization is suppressed for intermediate angles that exhibit two distinct local minima in the moiré potential (at AA region and saddle point (SP)) which become degenerate for the largest system (2.45°).

Photoionization Observables from Multi-Reference Dyson Orbitals Coupled to B-Spline DFT and TD-DFT Continuum.

We present a theoretical model to compute the accurate photoionization dynamical parameters (cross-sections, asymmetry parameters and orbital, or cross-section, ratios) from Dyson orbitals obtained with the multi-state complete active space perturbation theory to the second order (MS-CASPT2) method. Our new implementation of Dyson orbitals in OpenMolcas takes advantage of the full Abelian symmetry point group and has the corrected normalization. The Dyson orbitals are coupled to an accurate description of the electronic continuum obtained with a multicentric B-spline basis at the DFT and TD-DFT levels. Two prototype diatomic molecules, i.e., CS and SiS, have been chosen due to their smallness, which hides important correlation effects. These effects manifest themselves in the appearance of well-characterized isolated satellite bands in the middle of the valence region. The rich satellite structures make CS and SiS the perfect candidates for a computational study based on our highly accurate MS-CASPT2/B-spline TD-DFT protocol.

The Right Answer for the Right Reason: My Personal Goal for Quantum Chemistry.

A brief history of quantum theory is given to illustrate the barriers to progress caused by preconceived ideas. The biases in my own thinking which I had to overcome to approach the right answer for the right reason are discussed. This is followed by a personal autobiography illustrating how I have led a life of serendipity with no real sense of purpose. Chance events have shaped my life. The algorithms for which I am best known are briefly discussed. Then highlights from the many applications of theory to excited states, bonding in ice, spin properties and magnetism, (e,2e) shake-up spectra, and organic reactions are mentioned. This wide range of applications is mostly due to accidental collaboration with colleagues who sought my help. My real interest was in developing methods which could address these problems.

An overview of methods for deriving the radiative transfer theory from the Maxwell equations. II: Approach based on the Dyson and Bethe-Salpeter equations.

In this paper, the vector radiative transfer equation is derived by means of the vector integral Foldy equations describing the electromagnetic scattering by a group of particles. By Assuming that in a discrete random medium the positions of the particles are statistically independent and by applying the Twersky approximation to the order-of-scattering expansion of the total field, we derive the Dyson equation for the coherent field and the ladder approximated Bethe-Salpeter equation for the dyadic correlation function. Then, under the far-field assumption for sparsely distributed particles, the Dyson equation is reduced to the Foldy integral equation for the coherent field, while the iterated solution of the Bethe-Salpeter equation ultimately yields the vector radiative transfer equation.

Orbitals and the Interpretation of Photoelectron Spectroscopy and (e,2e) Ionization Experiments.

Electron momentum spectroscopy, scanning tunneling microscopy, and photoelectron spectroscopy provide unique information about electronic structure, but their interpretation has been controversial. This essay discusses a framework for interpretation. Although this interpretation is not new, we believe it is important to present this framework in light of recent publications. The key point is that these experiments provide information about how the electron distribution changes upon ionization, not how electrons behave in the pre-ionized state. Therefore, these experiments do not lead to a "selection of the correct orbitals" in chemistry and do not overturn the well-known conclusion that both delocalized molecular orbitals and localized molecular orbitals are useful for interpreting chemical structure and dynamics. The two types of orbitals can produce identical total molecular electron densities and therefore molecular properties. Different types of orbitals are useful for different purposes.

[Design of Dyson Flow Cytometry System].

In order to meet the needs of the flow cytometry for the simultaneous analysis of multiple fluorescence wavelengths and small volume, the design method of flow cytometry spectrum analysis system is presented by analyzing the characteristics of Dyson structure. And according to the method, a flow cytometry spectrum analysis system is disigned with Dyson type.The system's spectral range is 400 nm to 800 nm, the defocused spot size is less than the pixel size 24µ mm, the ransfer function value is above 0.8 at the Nyquist cut-off frequency 21 lp/mm,the spectral resolution is less than 3 nm, and the overall size is 83.54 mm×85.60 mm.The system has good optical performance and small volume, which meets the needs of the flow cytometry fluorescence spectral analysis. The outstanding innovation of this system is the application of Dyson light splitting structure and EMCCD detector which is high speed and high sensitivity.

Uncertainty Relation Based on Wigner-Yanase-Dyson Skew Information with Quantum Memory.

We present uncertainty relations based on Wigner-Yanase-Dyson skew information with quantum memory. Uncertainty inequalities both in product and summation forms are derived. It is shown that the lower bounds contain two terms: one characterizes the degree of compatibility of two measurements, and the other is the quantum correlation between the measured system and the quantum memory. Detailed examples are given for product, separable and entangled states.

Neutrinos to Astrovirology: Signatures.

In the 20th century, the concept of terrestrial life's unity was solidified, and the 21st century saw the emergence and establishment of astrovirology. To date, life originating beyond Earth has not been identified. The singular instance where NASA investigated potential microfossils in Martian ejecta found on Earth has since been refuted. This report suggests that a more comprehensive discussion and analysis of life's biosignatures and communication methods are essential. Such approaches are crucial not only to avoid overlooking the possible existence of extra-terrestrial intelligence (ETI) but also to prevent potential human infections that could arise from extra-terrestrial contact. In addition terrestrial infections by microorganism that originally derived from Earth and were returned, require investigation due to potential mutations and subsequent increased pathogenicity.

Probing rapidly-ionizing super-atom molecular orbitals in C60: a computational and femtosecond photoelectron spectroscopy study.

Super-atom molecular orbitals (SAMOs) are diffuse hydrogen-like orbitals defined by the shallow potential at the centre of hollow molecules such as fullerenes. The SAMO excited states differ from the Rydberg states by the significant electronic density present inside the carbon cage. We provide a detailed computational study of SAMO and Rydberg states and an experimental characterization of SAMO excited electronic states for gas-phase C(60) molecules by photoelectron spectroscopy. A large band of 500 excited states was computed using time-dependent density functional theory. We show that due to their diffuse character, the photoionization widths of the SAMO and Rydberg states are orders of magnitude larger than those of the isoenergetic non-SAMO excited states. Moreover, in the range of kinetic energies experimentally measured, only the SAMO states photoionize significantly on the timescale of the femtosecond laser experiments. Single photon ionization of the SAMO states dominates the photoelectron spectrum for relatively low laser intensities. The computed photoelectron spectra and photoelectron angular distributions are in good agreement with the experimental results.

Sir William Osler's fatal trip to Scotland: "Mrs M" and the University Grants Committee.

On 23 September 1919, Sir William Osler, after a telephone call from his friend Dyson Perrins, went to Glasgow where he saw a 40-year-old woman, Bethia Fulton Martin, in consultation with three local physicians. Osler called it "one of those remarkable Erythema cases (all sorts of skin lesions and three months on and off consolidation of both lower lobes)." Mrs Martin died 114 days later; her death certificate listed "angioneurotic oedema with chronic nephritis" and "tuberculous enlargement of the mediastinal lymph nodes." Osler died 18 days before Mrs Martin of complications from a respiratory infection acquired on his way home from Scotland. We discuss factors that possibly prompted Osler to go to Scotland, including his role with the newly formed University Grants Committee, and the differential diagnosis of the case, which is mainly between systemic lupus erythematosus and Henoch-Schönlein purpura.

From quarks and gluons to baryon form factors.

I briefly summarize recent results for nucleon and [Formula: see text] electromagnetic, axial and transition form factors in the Dyson-Schwinger approach. The calculation of the current diagrams from the quark-gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects.

CrasyDSE: A framework for solving Dyson-Schwinger equations.

Dyson-Schwinger equations are important tools for non-perturbative analyses of quantum field theories. For example, they are very useful for investigations in quantum chromodynamics and related theories. However, sometimes progress is impeded by the complexity of the equations. Thus automating parts of the calculations will certainly be helpful in future investigations. In this article we present a framework for such an automation based on a C++ code that can deal with a large number of Green functions. Since also the creation of the expressions for the integrals of the Dyson-Schwinger equations needs to be automated, we defer this task to a Mathematica notebook. We illustrate the complete workflow with an example from Yang-Mills theory coupled to a fundamental scalar field that has been investigated recently. As a second example we calculate the propagators of pure Yang-Mills theory. Our code can serve as a basis for many further investigations where the equations are too complicated to tackle by hand. It also can easily be combined with DoFun, a program for the derivation of Dyson-Schwinger equations. PROGRAM SUMMARY: Program title: CrasyDSE Catalogue identifier: AEMY _v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 49030 No. of bytes in distributed program, including test data, etc.: 303958 Distribution format: tar.gz Programming language: Mathematica 8 and higher, C++. Computer: All on which Mathematica and C++ are available. Operating system: All on which Mathematica and C++ are available (Windows, Unix, Mac OS). Classification: 11.1, 11.4, 11.5, 11.6. Nature of problem: Solve (large) systems of Dyson-Schwinger equations numerically. Solution method: Create C++ functions in Mathematica to be used for the numeric code in C++. This code uses structures to handle large numbers of Green functions. Unusual features: Provides a tool to convert Mathematica expressions into C++ expressions including conversion of function names. Running time: Depending on the complexity of the investigated system solving the equations numerically can take seconds on a desktop PC to hours on a cluster.

A non-perturbative study of the interplay between electron-phonon interaction and Coulomb interaction in undoped graphene.

In condensed-matter systems, electrons are subjected to two different interactions under certain conditions. Even if both interactions are weak, it is difficult to perform perturbative calculations due to the complexity caused by the interplay of two interactions. When one or two interactions are strong, ordinary perturbation theory may become invalid. Here we consider undoped graphene as an example and provide a non-perturbative quantum-field-theoretic analysis of the interplay of electron-phonon interaction and Coulomb interaction. We treat these two interactions on an equal footing and derive the exact Dyson-Schwinger (DS) integral equation of the full Dirac-fermion propagator. This equation depends on several complicated correlation functions and thus is difficult to handle. Fortunately, we find that these correlation functions obey a number of exact identities, which allows us to prove that the DS equation of full fermion propagator is self-closed. After solving this self-closed equation, we obtain the renormalized fermion velocity and show that its energy (momentum) dependence of renormalized fermion velocity is dominantly determined by the electron-phonon (Coulomb) interaction. In particular, the renormalized velocity exhibits a logarithmic momentum dependence and a non-monotonic energy dependence.

Bioinformation and Neutrino Communication.

Communications among civilizations may include self-descriptive bioinformation because pathogen dynamics exist in their astrobiology and astrovirology, which could become pathogenic upon actual contact. This information is of mutual benefit, if reciprocated. However, in contrast, the strategic counter-scenario of self-hidden civilizations is also discussed. Civilizations, including extra-terrestrial civilizations have been divided and stratified into three levels, using a wide non-linear logarithmic scale. The levels are based on their energy expenditures: level 1 is at 4x10^19 erg/sec; level 2 is at 4x10^33 erg/sec; and level 3 is at 4x10^44 erg/sec. Terrestrial civilization is currently below the entry level I. Particularly advanced civilizations, which are above the highest level, may engineer interstellar travel and could move their planets across interstellar distances. Communication among civilizations has always been of keen interest. In terms of ability to communicate among advanced civilizations, neutrinos may be used for galactic and inter-galactic communication, in addition to or instead of using electromagnetic radiation. Thus, at this juncture, deliberation and debate are essential to proceed with development of civilization and communication.

Evaluation of stress relaxation process of wood based on the eigenvalue distribution of near infrared spectra.

Wood is a highly heterogeneous composite material consisting of three major natural polymers featuring properties that can vary significantly among samples. We examined the stress relaxation of wood as a stochastic process. The eigenvalue distribution at each time was calculated from the near-infrared spectral matrix during the stress relaxation test. The eigenvalue motion was regarded as Dyson's Brownian motion. The first eigenvalue, which is equivalent to the Helmholtz free energy, gradually increased with time, indicating that the relaxation of wood exposed to change necessitates a more organised molecular configuration. The time evolutions of the Shannon entropy calculated from the probability associated with each energy eigenstate did not overlap between the inverse temperatures. Thus, the curves were smoothly shifted until continuous, thereby generating a master curve. The proposed method addresses the limitation of sample differences by assessing the behaviour of the statistical ensemble rather than that of the individual samples.

Mean field dynamics of some open quantum systems.

We consider a large number N of quantum particles coupled via a mean field interaction to another quantum system (reservoir). Our main result is an expansion for the averages of observables, both of the particles and of the reservoir, in inverse powers of [Formula: see text]. The analysis is based directly on the Dyson series expansion of the propagator. We analyse the dynamics, in the limit [Formula: see text], of observables of a fixed number n of particles, of extensive particle observables and their fluctuations, as well as of reservoir observables. We illustrate our results on the infinite mode Dicke model and on various energy-conserving models.

Photoelectron wave function in photoionization: plane wave or Coulomb wave?

The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion.

Angle-Dependent Ionization of Small Molecules by Time-Dependent Configuration Interaction and an Absorbing Potential.

The angle-dependence of strong field ionization of O2, N2, CO2, and CH2O has been studied theoretically using a time-dependent configuration interaction approach with a complex absorbing potential (TDCIS-CAP). Calculation of the ionization yields as a function of the direction of polarization of the laser pulse produces three-dimensional surfaces of the angle-dependent ionization probability. These three-dimensional shapes and their variation with laser intensity can be interpreted in terms of ionization from the highest occupied molecular orbital (HOMO) and lower lying orbitals, and the Dyson orbitals for the ground and excited states of the cations.

Local Ionization Dynamics Traced by Photoassisted Scanning Tunneling Microscopy: A Theoretical Approach.

For tracing the spatiotemporal evolution of electronic systems, we suggest and analyze theoretically a setup that exploits the excellent spatial resolution based on scanning tunneling microscopy techniques combined with the temporal resolution of femtosecond pump-probe photoelectron spectroscopy. As an example, we consider the laser-induced, local vibrational dynamics of a surface-adsorbed molecule. The photoelectrons released by a laser pulse can be collected by the scanning tip and utilized to access the spatiotemporal dynamics. Our proof-of-principle calculations are based on the solution of the time-dependent Schrödinger equation supported by the ab initio computation of the matrix elements determining the dynamics.