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**** ESF Programme ****
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**** RELATIVISTIC EFFECTS IN HEAVY ELEMENT CHEMISTRY ****
**** AND PHYSICS ****
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Newsletter No. 27 (October 28, 1997)
______________________________________________________________
Editor: Bernd Hess, hess@uni-bonn.de
Tel. 49-228-732920
FAX 49-228-732551
______________________________________________________________
The programme 'Relativistic Effects in Heavy-Element Chemistry and Physics'
('REHE') has been initiated by the European Science
Foundation in November 1992 and it is expected to run for 5 years, i.e.
from 1993 through 1997. The programme is intended to strengthen the in-
dicated "field" and to facilitate interactions between European scientists
concerned with related topics.
The 'Steering Committee' of the programme has at present the following
members:
E. J. Baerends (Amsterdam)
J.P. Daudey (Toulouse)
K. Faegri (Oslo)
I.P. Grant (Oxford)
B. Hess (Bonn, Vice-Chairman)
J. Karwowski (Torun)
P. Pyykko (Helsinki, Chairman)
K. Schwarz (Vienna)
A. Sgamellotti (Perugia)
C. Werner (ESF).
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--- E D I T O R I A L
Please send material for the forthcoming newsletter to my attention,
hess@uni-bonn.de
The newsletter will be sent out every second month around the 10th day
of the month. Contributions should arrive in Bonn until the end of the
preceding month.
| The next newsletter (#28) is scheduled for December 1997.
Please send material >by e/mail< that enables us to fill the
following topics in forthcoming newsletters
All REHE newsletters are available on www under URL
http://pcgate.thch.uni-bonn.de/tc/hess/esf/nl.html
see also the URL of the European Science Foundation
http://www.esf.c-strasbourg.fr
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--- F E L L O W S H I P S
In the framework of the REHE programme, there is support available
for visits of doctoral students and also for senior scientists at
institutions in a foreign partner country. This support covers visits
lasting 2-4 months ("long-term visits") which will give the holders
time to acclimatize to the methods used in the host laboratory as well as
short visits ("short-term visits") of only a few days.
Please send a short application detailing the project, the names of the
scientists involved and the aproximate date and duration of the visit
to either Pekka Pyykko or Bernd Hess. Please refer to REHE newsletter #16
for details.
Please indicate >who wants to go >when >where, >what shall be done and
>how much money (in FRF) is required.
As a rule, the steering committee members will decide on the applications
on occation of ther meetings.
Applications for visits that require decision in the interim time between
steering committee meetings may still be handled by means of consultation
within the steering group.
After the journey, a short report about the scientific accomplishments
is required. Please send a version by e-mail in a form suitable for
publication in a REHE newsletter to hess@uni-bonn.de
Should the planned dates of your stay change for any reason, you are
requested to notify the Chairman and the Vice-Chairman (preferrably by
e-mail) as soon as possible with a copy to the ESF.
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--- R E S E A R C H N E W S AND R E L A T E D I N F O R M A T I O N
Summaries of recent research or comments to it (up to 1 page),
which are of general interest to the 'REHE' community, may
be submitted by any colleague preferrably by E-mail to my attention.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
[communicated by Pekka Pyykko]
NEW VERSION OF THE 'RTAM' BIBLIOGRAPHY IN WWW
A new version, 4.0, of the Relativistic Theory of Atoms and
Molecules (RTAM) bibliography was made available on September 25
at the old address:
http://www.csc.fi/lul/rtam/
This version has 8804 references.
A 7-bit version with no French/German/Scandinavian/Spanish letters is given.
Pekka Pyykko
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
[communicated by J. Sienkiewicz]
Report on the visit of J. E. Sienkiewicz (Politechnika Gdanska,
Gdansk) to Mathematical Institute, Oxford (22 June to 5 September 1997)
During the visit the exchange effect in spin polarization of electron
scattered from heavy atoms like xenon and mercury has been
investigated. Also some partial wave analysis has been performed.
The motivation for this study was to understand better the spin
polarization mechanism and to make an effort to remove some
substantial discrepancies between theory and experiment which occur in
the case of xenon as the target atom at the energy of 1.5 eV.
Three types of calculations have been performed. First, with the use
of the relativistic scattering equation, where the spin-orbit
interaction as well as exchange between a projectile electron
and atomic electrons have been taken into account. Second, only exchange
has been retained in the scattering equation and the spin-orbit
interaction has been neglected. The third type of calculation has
involved the spin-orbit interaction and neglected exchange terms. In
the second type of calculations the scattering equations have been
solved in the non-relativistic limit. The spin-orbit interaction
term and two other terms, namely the Darwin term and the relativistic
mass correction term, have been made negligibly small. At low energy,
and correspondingly small projectile velocity, we do not
expect that any terms beside the spin-orbit interaction play
any part in the scattering process. The spin-orbit interaction
term gives rise to different scattering potentials for electrons
with different quantum numbers kappa and the same orbital quantum
number l. We have retained the same relativistic description of
target atom in all calculations and we have kept the relativistic
notation for the continuum orbital of the scattered electron in the
nonrelativistic limit. For different values of kappa and the same value
of l we have obtained different continuum orbitals due to different
exchange terms in scattering equation. The third type of calculation
omits the exchange terms in the scattering equations.
There are two other types of calculations where the spin polarization
vanishes for all scattering angles: calculations in the non-relativistic
limit in both atomic structure and scattering equations, and
calculations with the non-relativistic scattering equation without
exchange terms. Both these cases have been tested numerically.
Calculations for xenon with neglected spin-orbit interaction but with
exchange show only a single minimum at backward scattering angles.
This minimum is quite well-pronounced and shows the importance of spin
polarization by exchange. The situation for the mercury atom at the
same energy is quite different. Calculations show the very small
effect of exchange and the almost total dominance of the spin-orbit
interaction in the scattering process.
Partial wave analysis has shown that in the scattering from mercury
the overwhelming contributions to spin polarization comes from the two
lowest partial waves. Almost the entire effect is due to s- and
p-wave contributions. In the case of xenon, the spin polarization is
almost wholly attributable to three partial waves. Moreover, the
d-wave contribution is responsible for the two spin polarization
minima at the energy of 1.5 eV and from a theoretical point of view
both those minima should be visible in the experimental data.
An article concerning the above studies has been submitted to Journal
of Physics B: Atomic, Molecular and Optical Physics.
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--- C O N F E R E N C E N E W S
'Conference News' (in general they should NOT overrun about 1 page)
may be provided by organizers or their scientific secretaries. --
For meetings and workshops supported by ESF the submission of such
a report is a m u s t . To facilitate my job the reports should
be forwarded to my attention via E-mail.
Also please send information about conferences that might be of interest
for the members of the REHE community.
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[no material for this section in the current newsletter]
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--- P A P E R S F U N D E D B Y R E H E
>>> please send a preprint of papers funded by REHE to Bernd A. He\ss,
>>> Institut f\"ur Physikalische und Theoretische Chemie, Universit\"at Bonn,
>>> 53115 Bonn, Germany
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
[communicated by Anatoli Titov]
Herein I would like to inform you that the paper:
"Generalized Relativistic Effective Core Potential: Theoretical grounds"
by A.V.Titov and N.S.Mosyagin
that was supported by the REHE/ESF fellowship grants NN 14-95 and 22-95 is
published as
PNPI Preprint N 2186, (St.-Petersburg, 1997) 84 pp.
and submitted to Phys.Rev.A.
+++++
ABSTRACT:
The Generalized Relativistic Effective Core Potential (GRECP) method is
analyzed from theoretical and computational points of view. The
Hamiltonian in the case of the frozen core approximation is compared with
the Hamiltonian containing the GRECP operator. It is demonstrated that
the form of the GRECP operator can be derived from rather natural
physical grounds and the procedure of generation of the GRECP can be
justified theoretically.
Accuracy of the GRECP approximation in simulation of interactions and
densities in the valence and outer core regions and reliability of
simulation of interactions with the inner core electrons removed from
calculations with the GRECP are discussed.
Importance of additional terms with potentials for outer core
pseudospinors and terms with occupation numbers of outermost core shells
in expression for the GRECP operator is demonstrated on example of
calculations for Ag, Ba, Hg, Tl, and U atoms. Difference between the
outer core and valence potentials is analyzed. It is shown that the
two-component pseudospinors and the large components of four-component
spinors coincide with a very high accuracy in the valence region for the
same configuration states which are different from the generator state.
Problems of gaussian approximation caused by rather singular shapes of
the potentials are considered. Serious additional efforts should be taken
in order to reach required (very high) accuracy of approximation of the
numerical potentials by gaussians before they can be used in subsequent
molecular calculations.
+++++
KEYWORDS: Relativistic Effective Core Potential (Pseudopotential),
Molecule with heavy atoms, Electronic structure, {\it Ab initio} method
of relativistic calculation.
----------
"Enhancement of the electric dipole moment of the electron in BaF molecule"
by M.G.Kozlov, A.V.Titov, N.S.Mosyagin, and P.V.Souchko
(E-preprint: http://xxx.lanl.gov/abs/physics/9707011;
Phys.Rev.A (Rapid communic-s, v.56(5), 1 Nov. 1997)
ABSTRACT:
We report results of {\it ab initio} calculation of the spin-rotational
Hamiltonian parameters including $P$- and $P,T$-odd terms for the BaF
molecule. The ground state wave function of BaF molecule is found with the
help of the Relativistic Effective Core Potential method followed by the
restoration of molecular four-component spinors in the core region of
barium in the framework of a non-variational procedure. Core polarization
effects are included with the help of the atomic Many Body Perturbation
Theory for Barium atom. For the hyperfine constants the accuracy of this
method is about 5-10\%.
-----------
can be of interest for the REHE community and also included into the next
newsletter, especially, in connection with the corresponding calculations
by H.Ouiney {\it et al.} (which were reported in the previous REHE newsletter)
and, besides, in this paper, a technique of the pseudospinor's freezing is
applided that was earlier suggested in the framework of the REHE fellowship
program.
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--- P O S I T I O N S available
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[no material for this section in the current newsletter]
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--- P O S I T I O N S sought
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[no material for this section in the current newsletter]
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--- ADDRESS LIST
The REHE address list comprises 194 scientists as of October 28, 1997; the
next address list will be provided with newsletter no. 28
This newsletter is mailed to all collegues presently in the REHE mailing
list.
If you want your name added to the REHE mailing list, please complete the form
and send it back per e-mail to hess@uni-bonn.de
>>> PLEASE include TEL, FAX, E-MAIL <<<
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End of REHE Newsletter No. 27