Multi-photon above threshold ionization of multi-electron atoms and molecules using the R-matrix approach

We formulate a computationally efficient time-independent method based on the multi-electron molecular R-matrix formalism. This method is used to calculate transition matrix elements for the multi-photon ionization of atoms and molecules under the influence of a perturbative field. The method relies on the partitioning of space which allows us to calculate the infinite-range free-free dipole integrals analytically in the outer region, beyond the range of the initial bound wave function. This approach is valid for an arbitrary order, that is, any number of photons absorbed both in the bound and the continuum part of the spectrum (below- and above-threshold ionization). We calculate generalized multi-photon cross sections and angular distributions of different systems (H, He, $$\hbox {H}_{{2}}$$ H 2 , $$\hbox {CO}_{{2}}$$ CO 2 ) and validate our approach by comparison with data from the literature.

Эффективный способ нахождения матричных элементов оператора дипольного момента и поправок к энергии многоатомной молекулы с помощью теории возмущений в рамках формализма полиномов квантовых чисел

In the framework of quantum numbers polynomials, energy corrections and matrix elements of a dipolar-moment for polyatomic molecules are obtained up to the second order, and a detailed calculation algorithm is presented. The results obtained for the fundamental transition matrix elements are in good agreement with the literature data.

Thomas–Reiche–Kuhn (TRK) sum rule for interacting photons

The Thomas–Reiche–Kuhn (TRK) sum rule is a fundamental consequence of the position–momentum commutation relation for an atomic electron, and it provides an important constraint on the transition matrix elements for an atom. Here, we propose a TRK sum rule for electromagnetic fields which is valid even in the presence of very strong light–matter interactions and/or optical nonlinearities. While the standard TRK sum rule involves dipole matrix moments calculated between atomic energy levels (in the absence of interaction with the field), the sum rule here proposed involves expectation values of field operators calculated between general eigenstates of the interacting light–matter system. This sum rule provides constraints and guidance for the analysis of strongly interacting light–matter systems and can be used to test the validity of approximate effective Hamiltonians often used in quantum optics.

Finite-Field Calculations of Transition Properties by the Fock Space Relativistic Coupled Cluster Method: Transitions between Different Fock Space Sectors

Reliable information on transition matrix elements of various property operators between molecular electronic states is of crucial importance for predicting spectroscopic, electric, magnetic and radiative properties of molecules. The finite-field technique is a simple and rather accurate tool for evaluating transition matrix elements of first-order properties in the frames of the Fock space relativistic coupled cluster approach. We formulate and discuss the extension of this technique to the case of transitions between the electronic states associated with different sectors of the Fock space. Pilot applications to the evaluation of transition dipole moments between the closed-shell-like states (vacuum sector) and those dominated by single excitations of the Fermi vacuum (the 1h1p sector) in heavy atoms (Xe and Hg) and simple molecules of heavy element compounds (I2 and TlF) are reported.

Finite-Field Calculations of Transition Properties by the Fock Space Relativistic Coupled Cluster Method: Transitions between Different Fock Space Sectors

Reliable information on transition matrix elements of various property operators between molecular electronic states is of crucial importance for predicting spectroscopic, electric, magnetic and radiative properties of molecules. The finite-field technique is a simple and rather accurate tool for evaluating transition matrix elements of first-order properties in the frames of the Fock space relativistic coupled cluster approach. We formulate and discuss the extension of this technique to the case of transitions between the electronic states associated with different sectors of the Fock space. Pilot applications to the evaluation of transition dipole moments between the closed-shell-like states (vacuum sector) and those dominated by single excitations of the Fermi vacuum (the $1h1p$ sector) in heavy atoms (Xe, Hg) and simple molecules of heavy element compounds (I${}_2$, TlF) are reported.

Nuclear transition matrix elements for neutrinoless double-β decay within Rp-violating squark-neutrino mechanism

Within the squark-neutrino mechanism of [Formula: see text]-violating SUSY, sets of 12 nuclear transition matrix elements (NTMEs) are calculated for the neutrinoless double-[Formula: see text] decay [Formula: see text] of [Formula: see text]Zr, [Formula: see text]Mo, [Formula: see text]Pd, [Formula: see text]Te and [Formula: see text]Nd isotopes. Specifically, four sets of HFB wave functions generated with four different parametrizations of the pairing plus multipolar two-body interactions, dipole form factor and three different parametrizations of the Jastrow short-range correlations are employed in the calculation of NTMEs with two possible prescriptions for the hadronization, namely the two-nucleon mode and the pionic mode. Without (with) Miller–Spencer parametrization of short-range correlation, uncertainties in average NTMEs [Formula: see text] (QBM), [Formula: see text] (NRQM), [Formula: see text] (FF3) and [Formula: see text] turn out be 11–18% (29–37%), 11–16% (27–31%), 5–12% (13–17%) and 3–13% (9–15%), respectively.

Analysis of an Optical Lattice Methodology for Detection of Atomic Parity Nonconservation

We present an extension and a deepened analysis of a suggested experimental scheme for detecting atomic parity violation, previously published in Phys. Rev. A 2019, 100, 050101. The experimental concept is described in more detail and we compute new ab initio data necessary for assessing the plausibility of the approach. Original theoretical data for transition matrix elements on the electric dipole forbidden transition in caesium 6 s 2 S 1 / 2 – 5 d 2 D 3 / 2 are reported, as are a range of electric dipole matrix elements connected to the ground state 6s. The latter is used for an analysis of the wavelength-dependent light shift in Cs. A range of experimental details is presented, combined with a survey of realistic lasers parameters. These are adopted to project the feasibility of the scheme to eventually be capable of delivering data beyond the standard model of particle physics.