8,016 research outputs found
Pure spin-angular momentum coefficients for non-scalar one-particle operators in jj-coupling
A revised program for generating the spin-angular coefficients in
relativistic atomic structure calculations is presented. When compared with our
previous version [G.Gaigalas, S.Fritzsche and I.P.Grant, CPC 139 (2001) 263],
the new version of the Anco program now provides these coefficients for both,
scalar as well as non-scalar one-particle operators as they arise frequently in
the study of transition probabilities, photoionization and electron capture
processes, the alignment transfer through excited atomic states, collision
strengths, and in many other investigations.
The program is based on a recently developed formalism [G.Gaigalas,
Z.Rudzikas, and C.F.Fischer, J. Phys. B 30 (1997) 3747], which combines
techniques from second quantization in coupled tensorial form, the theory of
quasispin, and the use of reduced coefficients of fractional parentage, in
order to derive the spin-angular coefficients for complex atomic shell
structures more efficiently. By making this approach now available also for
non-scalar interactions, therefore, studies on a whole field of new properties
and processes are likely to become possible even for atoms and ions with a
complex structure
Maple procedures for the coupling of angular momenta. VI. LS-jj transformations
Transformation matrices between different coupling schemes are required, if a
reliable classification of the level structure is to be obtained for open-shell
atoms and ions. While, for instance, relativistic computations are
traditionally carried out in jj-coupling, a LSJ coupling notation often occurs
much more appropriate for classifying the valence-shell structure of atoms.
Apart from the (known) transformation of single open shells, however, further
demand on proper transformation coefficients has recently arose from the study
of open d- and f-shell elements, the analysis of multiple--excited levels, or
the investigation on inner-shell phenomena. Therefore, in order to facilitate a
simple access to LS jj transformation matrices, here we present an
extension to the Racah program for the set-up and the transformation of
symmetry-adapted functions. A flexible notation is introduced for defining and
for manipulating open-shell configurations at different level of complexity
which can be extended also to other coupling schemes and, hence, may help
determine an optimum classification of atomic levels and processes in the
future
Relativistic central--field Green's functions for the RATIP package
From perturbation theory, Green's functions are known for providing a simple
and convenient access to the (complete) spectrum of atoms and ions. Having
these functions available, they may help carry out perturbation expansions to
any order beyond the first one. For most realistic potentials, however, the
Green's functions need to be calculated numerically since an analytic form is
known only for free electrons or for their motion in a pure Coulomb field.
Therefore, in order to facilitate the use of Green's functions also for atoms
and ions other than the hydrogen--like ions, here we provide an extension to
the Ratip program which supports the computation of relativistic
(one--electron) Green's functions in an -- arbitrarily given -- central--field
potential \rV(r). Different computational modes have been implemented to
define these effective potentials and to generate the radial Green's functions
for all bound--state energies . In addition, care has been taken to
provide a user--friendly component of the Ratip package by utilizing features
of the Fortran 90/95 standard such as data structures, allocatable arrays, or a
module--oriented design.Comment: 20 pages, 1 figur
The Role of the Unconscious in the Perception of Risks
Dr. Fritzsche argues that our world is too rational and that the psychology of the unconscious, as developed by Jung, can be key to understanding responses to hazards and to resolving conflicts that arise in the political management of risks
The Moral Dilemma in the Social Management of Risks
Dr. Fritzsche offers data seen as demonstrating that irrational fears can lead to grotesque imbalances in social efforts devoted to preventing fatalities
Relativistic wave and Green's functions for hydrogen--like ions
The \textsc{Greens} library is presented which provides a set of C++
procedures for the computation of the (radial) Coulomb wave and Green's
functions. Both, the nonrelativistic as well as relativistic representations of
these functions are supported by the library. However, while the wave functions
are implemented for all, the bound and free--electron states, the Green's
functions are provided only for bound--state energies ). Apart from the
Coulomb functions, moreover, the implementation of several special functions,
such as the Kummer and Whittaker functions of the first and second kind, as
well as a few utility procedures may help the user with the set--up and
evaluation of matrix elements.Comment: 21 page
Program to calculate pure angular momentum coefficients in jj-coupling
A program for computing pure angular momentum coefficients in relativistic
atomic structure for any scalar one- and two-particle operator is presented.
The program, written in Fortran 90/95 and based on techniques of second
quantization, irreducible tensorial operators, quasispin and the theory of
angular momentum, is intended to replace existing angular coefficient modules
from GRASP92. The new module uses a different decomposition of the coefficients
as sums of products of pure angular momentum coefficients, which depend only on
the tensor rank of the interaction but not on its details, with effective
interaction strengths of specific interactions. This saves memory and reduces
the computational cost of big calculations signficantly
High-fidelity copies from a symmetric 1 to 2 quantum cloning machine
A symmetric 1 to 2 quantum cloning machine (QCM) is presented that provides
high-fidelity copies with for all pure (single-qubit)
input states from a given meridian of the Bloch sphere. \cor{Emphasize is
placed especially on the states of the (so-called) Eastern meridian, that
includes the computational basis states \ketm{0}, \ketm{1} together with the
diagonal state \ketm{+} = \frac{1}{\sqrt{2}} (\ketm{0}
+ \ketm{1}), for which suggested cloning transformation is shown to be
optimal.} In addition, we also show how this QCM can be utilized for
eavesdropping in Bennett's B92 protocol for quantum key distribution with a
substantial higher success rate than obtained for universal or equatorial
quantum copying.Comment: 2 figures, 20 reference
Complete one-loop corrections to the mass spectrum of charginos and neutralinos in the MSSM
The mass spectrum of the chargino--neutralino sector in the minimal
supersymmetric standard model (MSSM) is calculated at the one-loop level, based
on the complete set of one-loop diagrams. On-shell renormalization conditions
are applied to determine the counterterms for the gaugino-mass-parameters and the Higgsino-mass parameter . The input is fixed in terms of
three pole masses (two charginos and one neutralino); the other pole masses
receive a shift with respect to the tree-level masses, which can amount to
several GeV. The detailed evaluation shows that both the fermionic/sfermionic
loop contributions and the non-(s)fermionic loop contributions are of the same
order of magnitude and are thus relevant for precision studies at future
colliders.Comment: 19 pages, including 3 figures; corrected some typo
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