Lidia Smentek‐Mielczarek

Third order abinitio calculations of the f↔f transition amplitudes for ions across the lanthanide series

The behavior of various contributions to the f↔f transition amplitude defined up to the third order in perturbation theory is analyzed. Main attention is paid to the third‐order contributions which are due to electron correlation inside the rare earth ion and arise from the static and dynamic models. The discussion is based on the numerical results of exact ab initio calculations performed for Pr+3, Nd+3, Eu+3, Gd+3, Tb+3, and Tm+3 ions.

Third order abinitio calculations of amplitudes of two‐photon absorption for ions across the lanthanide series

The third‐order electron‐correlation theory of two‐photon absorption in rare earth ions in crystals has been extended by the effective operators arising from doubly excited configurations. The approach defined in terms of one‐particle effective operators has been applied to the Pr+3, Nd+3, Eu+3, Gd+3, Tb+3, and Tm+3 ions. The relative importance of third‐order contributions and their properties across the lanthanide series are presented. The discussion is based on the numerical results of exact ab initio calculations performed within the perturbed‐function approach.

Third‐order abinitio calculations of the intensity parameters for the Pr+3 ion in LaAlO3, NdAlO3, and LaCl3 hosts

The values of intensity parameters for the Pr+3 ion in LaAlO3, NdAlO3, and LaCl3 hosts evaluated with complete ab initio calculations based on the third‐order f↔f transition theory are reported. In this theory, the intensity parameters, in addition to the standard second‐order contributions, contain the static and dynamic third‐order contributions which arise from electron correlation within the central ion. In the numerical procedure performed, all the one‐particle effective operators which originate from singly excited intermediate configurations were included and the radial factors were evaluated within the perturbed‐function approach. For the first time the discussion of the influence of electron correlation upon the values of intensity parameters is presented, and a comparison with experiment is made.

Crystal field, ligand polarization and electron correlation third order contributions to the f↔f transition probabilities

A method for analysis of the influence of electron correlation inside the rare earth ion and polarization of ligands on the f↔f transition probabilities is presented. The approach is formulated by means of double perturbation theory and in terms of effective tensor operators. The detailed discussion of the structure of the third order contributions to the line strength is performed. The main attention is directed to the new term which represents both mechanisms simultaneously. The values of some third order contributions for [3 P]0-[3 H]4 and [3 P]0-[3 F]4 electric dipole transitions in Pr+3: LaCl3 are calculated.

Electron correlation third-order contributions to the electric dipole transition amplitudes of rare earth ions in crystals

A complete expression for the f↔f transition amplitude defined up to the third order in perturbation theory is presented. The third-order contributions are due to electron correlation inside the rare earth ion and arise from the static and dynamic models. The approach is formulated by means of double perturbation theory and in terms of effective tensor operators expressed by unit tensor operators. The discussion of the relative importance of various kinds of effective operators is based on the numerical results of test ab initio calculations performed within the perturbed function approach for the Pr+3 ion.

Intensities and asymmetry features of electronic Raman spectra of TmPO4. Third-order one-particle parametrization scheme

The intensities and polarization characteristics of the transitions from the ground state to the crystal field levels of the 3H6 multiplet of TmPO4 are analyzed and compared with experiment. Emphasis is directed toward the asymmetry features of the Raman spectra. The discussion is based on the results of ab initio calculations performed within the third‐order electron correlation theory formulated in terms of perturbed functions. The various contributions to the scattering tensor have been evaluated for the complete radial basis sets (including continuum states), and they represent the impact of the singly excited configurations 4fN−1l’, for l’=d,f,g.

Is ‘‘cross‐talk’’ between the lanthanide charge reservoir layers and superconducting planes in cuprates possible?

The powerful tool of the perturbed function approach has been used to create a theoretical model which explains the observed features and spectroscopic properties of rare earth ions in conducting and superconducting cuprates.

AB initio computation of the infrared spectra of alkoxycarbenes

Abstract Ab initio vibrational spectra (MP2/6-31G ∗ ) are presented for the cis and trans isomers of both methoxychlorocarbene and methylmethoxycarbene. Comparison of these computed spectra with the experimental spectra of these carbenes is made.

Third-order analysis of rotatory strengths of f ↔ f transitions in chiral lanthanide systems

The general expression for the rotatory strength of f ↔ f transitions in chiral lanthanide systems is presented. The approach is based on double perturbation theory, and the transition amplitude is defined within the static and dynamic models of central ion-ligand interactions. In order to include the perturbing influence of all single excitations from the 4f shell to one-electron states of given symmetry, the effective operators which contribute to the rotatory strength are expressed in terms of perturbed functions. In addition to the third-order electron correlation effective operators which have been already introduced into the theory of one- and two-photon processes in rare earth ions, new terms arising from the perturbing influence of the inter-space part of the even-rank crystal field potential are presented. The results of test ab initio calculations performed for Na3[Eu-(oxydiacetate)3].2NaClO4.6H2O are analysed in order to establish the relative importance of new effective operators in the theore...

Perturbative corrections to basis incompleteness in molecular SCF calculations

A unified summary is presented of the mathematical approach developed by McDowell for employing perturbation theory to correct for basis-set incompleteness in ab initio SCF calculations. Revised expressions for the corrections to the wavefunction both in terms of orbitals and spin-orbitals are presented with explicit incorporation of the spin variables. Employing H2O as an example, we show that this approach is considerably more powerful for computing molecular energies with standard basis sets than was indicated by previous work. In particular at the higher levels of approximation it accurately reproduces the effect of polarization functions in sets such as 6-31G* and 6-31G**. The equilibrium molecular structure of H2O was also computed by this approach and found to give good accuracy. In each case perturbing functions coupled to both occupied and virtual orbitals are required for acceptable results.