Relativistic study of parity-violating nuclear spin-rotation tensors

We present a four-component relativistic approach to describe the effects of the nuclear spin-dependent parity-violating (PV) weak nuclear forces on nuclear spin-rotation (NSR) tensors. The formalism is derived within the four-component polarization propagator theory based on the Dirac-Coulomb Hamiltonian. Such calculations are important for planning and interpretation of possible future experiments aimed at stringent tests of the standard model through the observation of PV effects in NSR spectroscopy. An exploratory application of this theory to the chiral molecules H2X2 (X = 17O, 33S, 77Se, 125Te, and 209Po) illustrates the dramatic effect of relativity on these contributions. In particular, spin-free and spin-orbit effects are even of opposite signs for some dihedral angles, and the latter fully dominate for the heavier nuclei. Relativistic four-component calculations of isotropic nuclear spin-rotation constants, including parity-violating electroweak interactions, give frequency differences of up to 4.2 mHz between the H2Po2 enantiomers; on the nonrelativistic level of theory, this energy difference is 0.1 mHz only.Fil: Aucar, Ignacio Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Borschevsky, Anastasia. University Of Groningen. Faculty Of Science And Engineering.; Países Bajo

Electronic Structure of Lr⁺ (Z = 103) from Ab Initio Calculations

The four-component relativistic Dirac–Coulomb Hamiltonian and the multireference configuration interaction (MRCI) model were used to provide the reliable energy levels and spectroscopic properties of the Lr+ ion and the Lu+ homolog. The energy spectrum of Lr+ is very similar to that of the Lu+ homolog, with the multiplet manifold of the 7s2, 6d1 7s1 and 7s1 7p1 configurations as the ground and low-lying excited states. The results are discussed in light of earlier findings utilizing different theoretical models. Overall, the MRCI model can reliably predict the energy levels and properties and bring new insight into experiments with superheavy ions

Relativistic coupled cluster calculation of Mossbauer isomer shifts of iodine compounds

Mossbauer isomer shifts of 129I and127I in the ICl, IBr and I 2 molecules are studied. Filatov's formulation is used, based on calculating the electronic energy change of the two systems involved in the Mossbauer. transition, the source and absorber. The energy difference between the transitions in the two systems determines the shift. The effects of relativity and electron correlation on the shifts are investigated. The exact two-component (X2C) and the four-component relativistic schemes give virtually identical results; the non-relativistic approach yields about 50% of the relativistic shifts. Electron correlation is included by coupled-cluster singles-and-doubles with perturbative triples [CCSD(T)]; it reduces Hartree-Fock shifts by 15%-20%. Basis sets are increased until the isomer shifts converge. The final results, calculated with the converged basis in the framework of the X2C Hamiltonian and CCSD(T) correlation, give an agreement of 10% or better with experimental data. [GRAPHICS

Ionization potentials and electron affinity of oganesson

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

State-specific ion mobilities of Lr^+ (Z = 103) in helium

Ion mobilities of Lr^+ (Z = 103) and of its lighter chemical homolog Lu^+ (Z = 71) in helium were calculated for the ground state ^1S_0 and the lowest metastable state ^3D_1. To this end we applied the multi-reference configuration interaction (MRCI) method to calculate the ion-atom interaction potentials in the different states. The Gram-Charlier approach to solving the Boltzmann equation was used to deduce the mobilities of the different electronic states, based on the calculated interaction potentials. We found that the zero-field ion mobilities are similar for the Lr^+ and Lu^+ ions. In addition, the ion mobilities of the different states are substantially different for temperatures above 100K. The relative differences between the mobilities of the ground and excited states at room temperature are about 15\% and 13\% for Lu^+ and Lr^+ ions, respectively, which should be sufficiently large enough to enable laser resonance chromatography (LRC) of these ions.Comment: 8 pages, 4 figures, 4 table

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

The nuclear anapole moment interaction in BaF from relativistic coupled cluster theory

We present high accuracy relativistic coupled cluster calculations of the P-odd interaction coefficient $W_A$ describing the nuclear anapole moment effect on the molecular electronic structure. The molecule under study, BaF, is considered a promising candidate for the measurement of the nuclear anapole moment, and the preparation for the experiment is now underway [Altunas et al., Phys. Rev. Lett. 120, 142501 (2018)]. Influence of various computational parameters (size of the basis set, treatment of relativistic effects, and treatment of electron correlation) on the calculated $W_A$ coefficient is investigated and a recommended value of 147.7 Hz with an estimated uncertainty of 1.5% is proposed.Comment: 9 pages, 3 figures, 3 tables, minor changes, the published versio

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

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