Krzysztof Zberecki

Nuclear tetrahedral configurations at spin zero

The possibility of the existence of stable tetrahedral deformations at spin zero is investigated using the Skyrme-HFBCS approach and the generator coordinate method (GCM). The study is limited to nuclei in which the tetrahedral mode has been predicted to be favored on the basis of non-self-consistent models. Our results indicate that a clear identification of tetrahedral deformations is unlikely because they are strongly mixed with the axial octupole mode. However, the excitation energies related to the tetrahedral mode are systematically lower than those of the axial octupole mode in all the nuclei included in this study.

SKYRME-HARTREE-FOCK AND HARTREE-FOCK-BOGOLYUBOV CALCULATIONS FOR NUCLEI WITH TETRAHEDRAL DEFORMATION

Hartree-Fock-Bogolyubov solutions corresponding to the tetrahedral deformation are found in six tetrahedrally doubly-magic nuclei. Values of the β32 deformation, depths of the tetrahedral minima, and their energies relative to the co-existing quadrupole minima are determined for several versions of the Skyrme force. Reduction of the tetrahedral deformation energies by pairing correlations is quantitatively analysed. In light nuclei, shallow tetrahedral minima are found to be the lowest in energy, while in heavy nuclei, the minima are deeper but appear at a few MeV of excitation.

Unique magnetic and thermoelectric properties of chemically functionalized narrow carbon polymers

We analyze magnetic, transport and thermoelectric properties of narrow carbon polymers, which are chemically functionalized with nitroxide groups. Numerical calculations of the electronic band structure and the corresponding transmission function are based on density functional theory. Transport and thermoelectric parameters are calculated in the linear response regime, with particular interest in charge and spin thermopowers (charge and spin Seebeck effects). Such nanoribbons are shown to have thermoelectric properties described by large thermoelectric efficiency, which makes these materials promising from the application point of view.

Tetrahedral correlations in 80 Zr and 98 Zr

Axial octupole and tetrahedral correlations in 80 Zr and 98 Zr have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.

QUANTUM FLUCTUATIONS AND STABILITY OF TETRAHEDRAL DEFORMATIONS IN ATOMIC NUCLEI

The possible existence of stable axial octupole and tetrahedral deformations is investigated in 80Zr and 98Zr. HFBCS calculations with parity projection have been performed for various parametrizations of the Skyrme energy functional. The correlation and excitation energies of negative parity states associated with shape fluctuations have been obtained using the generator coordinate method (GCM). The results indicate that in these nuclei both the axial octupole and tetrahedral deformations are of dynamic character and possess similar characteristics. Various Skyrme forces give consistent results as a function of these two octupole degrees of freedom both at the mean-field level as well as for configuration mixing calculations.

Tetrahedral correlations in Zr 80 and Zr 98

Axial octupole and tetrahedral correlations in 80 Zr and 98 Zr have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.

Tetrahedral correlations in 80Zr and 98Zr

Axial octupole and tetrahedral correlations in 80 Zr and 98 Zr have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.

Tetrahedral correlations in Zr80 and Zr98

Axial octupole and tetrahedral correlations in 80 Zr and 98 Zr have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.

Tetrahedral correlations inZr80andZr98

Axial octupole and tetrahedral correlations in 80 Zr and 98 Zr have been investigated using the generator coordinate method, applied to a basis generated by Skyrme Hartree-Fock+BCS calculations. We focus on the possible presence of states with tetrahedral symmetry and their stability with respect to octupole vibrations. We show that pairing significantly reduces the stability of the tetrahedral configuration and that a shallow mean-field tetrahedral minimum coexists with an axial octupole minimum. The contributions to the correlation energies coming from the tetrahedral degree of freedom and octupole axial deformation are discussed.