Covariant density functional theory for excited states in nuclei far from stability*
Abstract
Investigations of nuclei far from stability are presently at the forefront of nuclear science. Density functional theory (DFT) is an important tool for a universal description of medium heavy and heavy systems. Because of the consistent treatment of spin degrees of freedom static and dynamic versions of covariant density functional Theory (CDFT) provide a very successful description of nuclear properties all over the periodic table. Excited states are treated in time dependent density functional theory (TDDFT) which is treated in different approximations:a) On the mean field level the relativistic quasiparticle random phase approximation (RQRPA) is used to investigate the multipole response in spherical and deformed nuclei far from stability, in particular low-lying modes [1], giant resonances [2], spin-isospin modes, scissor modes [3] and new exotic resonances, such as pygmy [4] or toroidal modes.b) Going beyond the mean field approximation, an energy dependent self-energy is constructed by coupling of the single particle motion to low-lying surface modes. This leads to an enhanced level density at the Fermi surface and an induced interaction in the resulting Bethe-Salpeter equation, which is solved in the time blocking approximation (TBA) [5]. No additional parameters are used and double counting is avoided by a proper subtraction method. This method is applied in several isotopic chains of spherical nuclei for the investigation of the width of giant resonances and of the coupling of low-lying dipole excitations to complex configurations [6].c) In transitional nuclei a theory is developed which uses the relativistic generator coordinate method (RGCM) as a basis to perform configuration mixing calculations of angular momentum and particle number projected wave functions [7] and to derive a collective hamiltonian in five quadrupole degrees of freedom [8]. This allows to calculate spectra of transitional nuclei and provides a microscopic interpretation of quantum phase transitions in finite fermion systems [9]. A number of illustrative calculations are presented and they are compared with results obtained in non-relativistic models based on Skyrme and Gogny effective interactions.[1] A. Ansari and P. Ring, Phys. Rev. C74, 054313 (2006).[2] J. Daoutidis and P. Ring, Phys. Rev. C80, 024309 (2009).[3] D. Pe~na Arteaga, E. Khan, and P. Ring, Phys. Rev. C79, 034311 (2009).[4] N. Paar, P. Ring, T. Nik_si_c, and D. Vretenar, Phys. Rev. C67, 034312 (2003).[5] E. Litvinova, P. Ring, and V. I. Tselyaev, Phys. Rev. C78, 014312 (2008).[6] E. Litvinova, P. Ring, V. I. Tselyaev, and K. Langanke, Phys. Rev. C79, 054312(2009).[7] J.-M. Yao, J. Meng, P. Ring, and D. Pe~na Arteaga, Phys. Rev. C79, 044312 (2009).[8] T. Nik_si_c, Z. P. Li, D. Vretenar, L. Pr_ochniak, J. Meng, and P. Ring, Phys. Rev. C79, 034303 (2009).[9] T. Nik_si_c, D. Vretenar, G. A. Lalazissis, and P. Ring, Phys. Rev. Lett. 99, 092502 (2007). * Work was supported in part by the DFG cluster of excellence Origin and Structure of the Universe(www.universe-cluster.de).
Black holes are our best guide towards understandingproperties of a quantum theory of gravity. On one hand, the study ofblack holes has revolutionized our understanding of string theory as awhole, and on the other hand string theory has come a long way inaddressing puzzles associated with black holes. In this talk I willprovide an overview of these exciting developments. I will discussthat a lot more can be learned about black holes using the hiddensymmetries of string/supergravity theories. I will conclude with somerecent ideas about the microscopic understanding of rotating extremalblack holes.
10/01/2011 at 4:00 pm
Prof. S. Nozaki, University of Electro-Communications, Tokyo, Japan
Biresh Patel Memorial Lecture 2011
Lecture Hall Block A, Institute of Physics
Document Date:
Photo-Modification and Synthesis of Semiconductor Nanocrystals
Photo-Modification and Synthesis of Semiconductor Nanocrystals
Abstract
The ultimate goal of nanofabrication is to control the size and positioning. We propose a simple and innovative way to achieve the goal by making the best use of a strong photon-nanoparticle interaction. Because of its large surface to volume ratio and carrier confinement in a nanoparticle, the semiconductor nanoparticle can be easily modified or synthesized by the light irradiation. We have observed two unique phenomena to manifest the photon-nanoparticle interaction: photo-oxidation and photo-synthesis. In both photo-oxidation and photo-synthesis, the sizes are self-limited to the photon energy of monochromatic light such as laser and are well controlled.
07/01/2011 at 4:00 pm
Mr. Santosh Kumar Das, VECC, Kolkata
NP Seminar
Lecture Hall Block A, Institute of Physics
Document Date:
Characterizing quark gluon plasma by heavy flavors
Study of Vapor Deposition Polymerization Using Monte Carlo Growth Model
Abstract
Morphological scaling properties of linear polymer films grown by vapor deposition polymerization (VDP) using 1+1D Monte Carlosimulations will be discussed in this talk. The lattice model implements the basicprocesses of random angle ballistic deposition (F), free-monomer diffusion (D), and monomer adsorption along with other dynamical processes of polymer chaininitiation,extension, and merger. The ratio G=D/F is found to have a strong influence on the polymer film morphology. Spatial and temporal behavior of kinetic roughening has been extensively studied using finite-length scaling and height-heightcorrelations. The scaling analysis has been performed within no-overhangapproximation andrelevant scaling exponents for film-interface evolution have been studied forvarying free-monomer diffusion.
