Ionization potentials and electron affinity of oganesson with relativistic coupled cluster method

We present high accuracy relativistic coupled cluster calculations of the first and second ionisation potentials and the electron affinity of the heaviest element in the Periodic Table, Og. The results were extrapolated to the basis set limit and augmented with the higher order excitations (up to perturbative quadruples), the Breit contribution, and the QED self energy and vacuum polarisation corrections. We have performed an extensive investigation of the effect of the various computational parameters on the calculated properties, which allowed us to assign realistic uncertainties on our predictions. Similar study on the lighter homologue of Og, Rn, yields excellent agreement with experiment for the first ionisation potential and a reliable prediction for the second ionisation potential

Material Size Dependence on Fundamental Constants

Precise experimental setups for detection of variation of fundamental constants, scalar dark matter, or gravitational waves, such as laser interferometers, optical cavities and resonant-mass detectors, are directly linked to measuring changes in material size. Here we present calculated and experiment-derived estimates for both $\alpha$- and $\mu$-dependence of lattice constants and bond lengths of selected solid-state materials and diatomic molecules that are needed for interpretation of such experiments

Molecular enhancement factors for P, T-violating eEDM in BaCH3_3 and YbCH3_3 symmetric top molecules

High-precision tests of fundamental symmetries are looking for the parity- (P), time-reversal- (T) violating electric dipole moment of the electron (eEDM) as proof of physics beyond the Standard Model. Particularly, in polyatomic molecules, the complex vibrational and rotational structure gives the possibility to reach high enhancement of the P, T-odd effects in moderate electric fields. Additionally, it is possible to increase the statistical sensitivity by using laser cooling. In this work, we calculate the P, T-odd electronic structure parameters $W_\mathrm{d}$ and $W_\mathrm{s}$ for the promising candidates BaCH$_3$ and YbCH$_3$ for the interpretation of future experiments. We employ high-accuracy relativistic coupled cluster methods and systematically evaluate the uncertainties of our computational approach. Compared to other Ba- and Yb-containing molecules, BaCH$_3$ and YbCH$_3$ exhibit larger $W_\mathrm{d}$ and $W_\mathrm{s}$ associated to increased covalent character of the M--C bond. The calculated values are $3.22\pm 0.11 \times 10^{24}\frac{h\text{Hz}}{e\text{cm}}$ and $13.80\pm 0.35 \times 10^{24}\frac{h\text{Hz}}{e\text{cm}}$ for $W_\mathrm{d}$, and $8.42\pm0.29$~$h$kHz and $45.35\pm1.15$~$h$kHz for $W_\mathrm{s}$, in BaCH$_3$ and YbCH$_3$, respectively. The robust, accurate, and cost-effective computational scheme reported in this work makes our results suitable for extracting the relevant fundamental properties from future measurements and also can be used to explore other polyatomic molecules sensitive to various violations of fundamental symmetries

Large Vibrationally Induced Parity Violation Effects in CHDBrI+^+ −- A Promising Candidate for Future Experiments

The isotopically chiral molecular ion CHDBrI$^+$ is identified as an exceptionally promising candidate for the detection of parity violation in vibrational transitions. The largest predicted parity-violating frequency shift reaches 1.8 Hz for the hydrogen wagging mode which has a sub-Hz natural line width and its vibrational frequency auspiciously lies in the available laser range. In stark contrast to this result, the parent neutral molecule is two orders of magnitude less sensitive to parity violation. The origin of this effect is analyzed and explained. Precision vibrational spectroscopy of CHDBrI$^+$ is feasible as it is amenable to preparation at internally low temperatures and resistant to predissociation, promoting long interrogation times (Landau et al.). The intersection of these properties in this molecular ion places the first observation of parity violation in chiral molecules within reach

Quadratic Word Equations with Length Constraints, Counter Systems, and Presburger Arithmetic with Divisibility

Word equations are a crucial element in the theoretical foundation of constraint solving over strings, which have received a lot of attention in recent years. A word equation relates two words over string variables and constants. Its solution amounts to a function mapping variables to constant strings that equate the left and right hand sides of the equation. While the problem of solving word equations is decidable, the decidability of the problem of solving a word equation with a length constraint (i.e., a constraint relating the lengths of words in the word equation) has remained a long-standing open problem. In this paper, we focus on the subclass of quadratic word equations, i.e., in which each variable occurs at most twice. We first show that the length abstractions of solutions to quadratic word equations are in general not Presburger-definable. We then describe a class of counter systems with Presburger transition relations which capture the length abstraction of a quadratic word equation with regular constraints. We provide an encoding of the effect of a simple loop of the counter systems in the theory of existential Presburger Arithmetic with divisibility (PAD). Since PAD is decidable, we get a decision procedure for quadratic words equations with length constraints for which the associated counter system is \emph{flat} (i.e., all nodes belong to at most one cycle). We show a decidability result (in fact, also an NP algorithm with a PAD oracle) for a recently proposed NP-complete fragment of word equations called regular-oriented word equations, together with length constraints. Decidability holds when the constraints are additionally extended with regular constraints with a 1-weak control structure.Comment: 18 page

Chiral molecule candidates for trapped ion spectroscopy by ab-initio calculations: from state preparation to parity violation

Parity non-conservation (PNC) due to the weak interaction is predicted to give rise to enantiomer dependent vibrational constants in chiral molecules, but the phenomenon has so far eluded experimental observation. The enhanced sensitivity of molecules to physics beyond the Standard Model (BSM), has led to substantial advances in molecular precision spectroscopy, and these may be applied to PNC searches as well. Specifically, trapped molecular ion experiments leverage the universality of trapping charged particles to optimize the molecular ion species studied toward BSM searches, but in searches for PNC only a few chiral molecular ion candidates have been proposed so far. Importantly, viable candidates need to be internally cold and their internal state populations should be detectable with high quantum efficiency. To this end, we focus on molecular ions that can be created by near threshold resonant two-photon ionization and detected via state-selective photo-dissociation. Such candidates need to be stable in both charged and neutral chiral versions to be amenable to these methods. Here, we present a collection of suitable chiral molecular ion candidates we have found, including CHDBrI$^+$ and CHCaBrI$^+$, that fulfill these conditions according to our \textit{ab-initio} calculations. We find that organo-metallic species have a low ionization energy as neutrals and relatively high dissociation thresholds. Finally, we compute the magnitude of the PNC values for vibrational transitions for some of these candidates. An experimental demonstration of state preparation and readout for these candidates will be an important milestone toward measuring PNC in chiral molecules for the first time.Comment: 14 pages, 3 figures and supplementary informatio

Shared Histories of Co-evolution May Affect Trophic Interactions in a Freshwater Community Dominated by Alien Species

Interactions occurring between species in multiple invaded freshwater ecosystems are often difficult to observe and study. Studies on invasive alien species typically focus on single species, and, when the species community is exclusively composed of alien species, their interactions, eventual facilitation and hindering processes are very scarcely assessed. To investigate such a community, the species community in the Arno River (Tuscany, Italy) was examined as a model system using the combined approach of stable isotopes and dietary analyses. Established alien species have formed a pyramid shaped community with the European catfish Silurus glanis and the North American channel catfish Ictalurus punctatus in the apex position, followed by opportunistic predatory (Lepomis gibbosus) and omnivore (Alburnus alburnus, Cyprinus carpio, Barbus barbus, Pseudorasbora parva, Padogobius sp., Tinca tinca) species. These species were observed to feed on a variety of primary producers (Myriophyllum sp., Potamogeton sp., Phragmites australis) and consumers (aquatic insects, molluscs, Dikerogammarus villosus, Procambarus clarkii, Palaemon antennarius, tadpoles). Remarkably, the channel catfish Ictalurus punctatus showed an ontogenetic niche shift, with juveniles occupying a slightly higher trophic position than mature individuals. Pseudorasbora parva and A. alburnus showed a strong niche overlap, with the former having a wider niche. Such wide niches were also found for the invasive crustaceans D. villosus and P. clarkii. Outgoing from our findings, we suggest that life-history and geographic origin play a role in determining competition and interaction type among alien species, with species from the same geographic area showing a lower potential to compete than species from different areas, hence affecting their potential impact on native species

Optical and magneto-optical behavior of Cerium Yttrium Iron Garnet thin films at wavelengths of 200–1770 nm

Magneto-optical cerium-substituted yttrium iron garnet (Ce:YIG) thin films display Faraday and Kerr rotation (rotation of light polarisation upon transmission and reflection, respectively) as well as a nonreciprocal phase shift due to their non-zero off-diagonal permittivity tensor elements, and also possess low optical absorption in the near-infrared. These properties make Ce:YIG useful in providing nonreciprocal light propagation in integrated photonic circuits, which is essential for accomplishing energy-efficient photonic computation and data transport architectures. In this study, 80 nm-thick Ce:YIG films were grown on Gadolinium Gallium Garnet substrates with (100), (110) and (111) orientations using pulsed laser deposition. The films had bulk-like structural and magnetic quality. Faraday and Kerr spectroscopies along with spectroscopic ellipsometry were used to deduce the complete permittivity tensor of the films in the ultraviolet, visible and near-infrared spectral region, and the magneto-optical figure of merit as a function of wavelength was determined. The samples showed the highest IR Faraday rotation reported for thin films of Ce:YIG, which indicates the importance of this material in development of nonreciprocal photonic devices.National Science Foundation (U.S.)Semiconductor Research Corporation. Function Accelerated nanoMaterial Engineerin

Optically Gated Terahertz-Field-Driven Switching of Antiferromagnetic CuMnAs

We show scalable and complete suppression of the recently reported terahertz-pulse-induced switching between different resistance states of antiferromagnetic CuMnAs thin films by ultrafast gating. The gating functionality is achieved by an optically generated transiently conductive parallel channel in the semiconducting substrate underneath the metallic layer. The photocarrier lifetime determines the timescale of the suppression. As we do not observe a direct impact of the optical pulse on the state of CuMnAs, all observed effects are primarily mediated by the substrate. The sample region of suppressed resistance switching is given by the optical spot size, thereby making our scheme potentially applicable for transient low-power masking of structured areas with feature sizes of about 200 nm and even smaller