IUCr COMMISSION NEWS
Contributions intended for this section should be submitted to The Executive Secretary, International Union of
Crystallography, 5 Abbey Square, Chester CH1 2H U, England.
COMMISSION ON CHARGE, SPIN AND MOMENTUM approximately 100 participants. The stimulating
DENSITIES and agreeable social activities offered by the
organizers were highly appreciated. The program
Acta Cryst. (1989). A45, FC15-FCI 7 included the following invited contributions:
J. R. Schneider (Berlin, FRG): New Frontiers in
N e w s l e t t e r No. 1 Charge Densities.
J. B. Forsyth (Rutherford Laboratory, UK): New
Following a suggestion by M. Nardelli, President Frontiers in Spin Densities.
of the International Union of Crystallography, S. Manninen (Helsinki, Finland): New Frontiers
the Commission decided to publish an annual in Momentum Densities.
n e w s l e t t e r , in general after the S a g a m o r e
S. W. Lovesey (Rutherford Laboratory, UK): The
Meeting, the Gordon Research Conference on Companionship of Neutron and Photon
Chemical Bonding or the Congress of the IUCr. Magnetic Scattering in Condensed Matter
The newsletter is intended to inform those Research.
i n t e r e s t e d in the field of charge, spin and
D. Feil (Enschede, Netherlands): Charge Density
momentum density studies of the activities of the Distribution and Chemical Bonding.
Commission, especially new scientific projects
and related meetings. R. F. Stewart (Pittsburgh, USA): Electrostatic
The C o m m i s s i o n on C h a r g e , Spin and Potentials and Energies from X-ray Diffraction
Momentum Densities supports new experiment-
al and t h e o r e t i c a l concepts in this inter- K. Hermansson (Uppsala, Sweden): Electronic
disciplinary field of research. The interplay Density Distribution, Intermolecular Potentials
between experiment and theory is considered and Molecular Mechanics.
essential for progress in this field and the L. Leiserowitz (Rehovot, Israel): Crystal Growth
Commission organizes meetings where these two and Electron Density in Organic Molecules.
aspects are well represented and s t i m u l a t e s V. S. Urusov (Moscow, USSR): Electron Density
common projects. A major effort is made to bring Distribution and Crystal Properties.
researchers from various laboratories together, K. Schwarz (Vienna, Austria): Electronic
in o r d e r to cross-check the e x p e r i m e n t a l Structure Calculations of Transition Metals and
techniques applied and to make developments Alloys.
available to a larger community. D. E. Ellis (Evanston, USA): Defect Structure
In this newsletter details are given of the Studies of Transition Metal Compounds.
Sagamore IX Conference held in Luso, Portugal,
M. M. R. Costa (Coimbra, Portugal): Electron
26 June-2 July 1988, of a two-day workshop on Densities in Transition Metals.
density matrices held in Coimbra, Portugal,
25-26 June 1988, and of new scientific projects. G. H. Lander (Karlsruhe, FRG): X-ray Studies of
Finally, a complete list of the members of the Magnetic Properties in Actinides.
Commission, together With their addresses, is M. J. Cooper (Warwick, UK): Magnetic X-ray
given in order to facilitate communication. Scattering.
Please contact a Commission member whenever W. Schfilke (Dortmund, FRG): Inelastic
you have suggestions or questions related to Scattering of Synchrotron Radiation.
charge, spin and momentum densities. M. Nielsen (Roskilde, Denmark): Surface
Structures and Phase Transitions Studied by X-
Sagamore IX in Luso ray Diffraction.
The meeting was organized by L. Alte da Veiga, G. P. Felcher (Chicago, USA): Grazing Incidence
M. M. R. Costa, M. J. M. de Almeida, L. R. Studies: Neutrons.
Andrade, A. Matos Beja and J. A. Paixao from S. Berko (Waltham, USA): Positronium Velocity
the Physics Department of Coimbra University Spectroscopy of the Electronic Structure of Metal
and was considered as most successful by the Surfaces.
FC16 FAST COMMUNICATIONS
About 60 posters were presented in three N e w Commission projects
sessions. The conference proceedings will be
V. Smith (Department of Chemistry, Queen's
published in Portugaliae Physica.
U n i v e r s i t y , K i n g s t o n , O n t a r i o K 7 L 3N6,
Canada) and W. Weyrich will devise a project on
Workshop on density matrices density matrices with emphasis on: (a) silicon, for
Experimental charge and momentum density which many experimental data and theoretical
studies yield complementary information on the calculations are available; and (b) other suitable
ground-state wavefunction of a system. One- compounds, still to be determined.
particle density matrices are considered the most E. D. Maslen (Crystallography Centre, Univ-
appropriate quantity for combining the two types ersity of Western Australia, Nedlands, Western
of information; their diagonal e l e m e n t s are Australia 6009, Australia) and D. Fell, assisted
related to the charge, the off-diagonal elements by K. Hermansson, will write a feasibility study
to the momentum density. In order to acquaint on electron densities and atomic charges in ionic
the c o m m u n i t y with this approach, and in compounds such as perovskites and organic salts.
preparation for a possible Commission project, D. This will indicate suitable compounds and
Fell, J. R. Schneider, W. Schfilke, L. Alte da appropriate questions, and will be presented at
Veiga and M. J. M. de Almeida organized a the next Gordon R e s e a r c h C o n f e r e n c e on
workshop on Density Matrices as Intermediates Chemical Bonding, in summer 1989.
between Wavefunctions and Experiments in J. R. Schneider, together with S. Berko, will
Coimbra, preceding Sagamore IX. The following initiate a workshop on the various experimental
lectures were presented: techniques probing the bulk electronic properties
V. Smith J r (Kingston, Canada): Basic Theory of With respect to Commission p r o j e c t s the
Density Matrices. following rule is adopted: A project is undertaken
for two years. It r e q u i r e s the i n i t i a t i v e of
G. E. W. Bauer (Eindhoven, Netherlands): The
Energy Electron Density Relationship. somebody - member of the Commission or not - to
extend its duration.
D. Fell (Enschede, Netherlands): Examples of
Density Matrices of Simple Systems. Sagamore X
C. Pisani (Torino, Italy): Density Matrices of
Crystals. The next Sagamore Conference on Charge, Spin
and M o m e n t u m D e n s i t i e s will be held in
J. R. Schneider (Berlin, FRG): Experimental Konstanz, FRG, at the end of August 1991. W.
Methods to Obtain Charge and Momentum
Densities. Weyrich (Fakult/it ffir Chemic, U n i v e r s i t / i t
Konstanz, Postfach 5560, D-7750 Konstanz 1,
W. Schtilke (Dortmund, FRG): Experimental FRG) is the C h a i r m a n of the O r g a n i z i n g
Methods to Obtain the Off-Diagonal Terms. Committee.
S. R. Gadre (Pune, India): From Positional
Density to Momentum Density. Members of the Commission
L. Massa (New York, USA): From Experiment to
Wavefunction. Professor S. Berko
W. Weyrich (Konstanz, FRG): Experimental Physics Department, Brandeis University,
Results on Off-Diagonal Terms and Conversion Waltham, MA 02154, USA.
Dr J.-X. Boucherle,
Proceedings of the workshop will be published CENG, DRF/DN, BP 85 X,
in Portugaliae Physica. F-38041 Grenoble CEDEX, France.
Magnetic form factors Professor D. E. Ellis,
Following a suggestion by the IUCr Commission Physics Department, Northwestern University,
on Neutron Diffraction, J.-X. Boucherle prepared Evanston, IL 60201, USA.
an updated compilation of magnetic form factors
and magnetization densities. Anyone interested Professor D. Fell
in o b t a i n i n g a copy should c o n t a c t J.-X. Chemical Physics Laboratory,
Boucherle (CENG, DRF/DN, 85 X, F-38041 Twente University of Technology, PO Box 217,
Grenoble CEDEX, France). 7500 AE Enschede, The Netherlands.
F A S T COMMUNICATIONS FC17
Dr J. B. Forsyth Professor M. Nardelli (ex officio: President of the
SERC Rutherford Laboratory, IUCr)
Neutron Division, Chilton, Didcot, Instituto di Chimica Generale ed Inorganica,
Oxon OXll 0QX, UK. Universit~ di Parma,Viale delle Scienze,
1-43100 Parma, Italy.
Dr Kersti Hermansson
Institut of Chemistry, Professor J. R. Schneider (Chairman)
University of Uppsala, Hahn-Meitner-Institut, Abt. C1,
PO Box 531, S-75121 Uppsala, Glienicker Str. 100, D-1000 Berlin 39, FRG.
Professor W. Schtilke
Professor F. L. Hirshfeld Institut ftir Physik,Universit~it Dortmund,
Weizmann Institute of Science, Otto-Hahn-Str., D-4600 Dortmund 50, FRG.
Rehovot 76100, Israel.
Dr H. G. Smith (ex officio: Chairman of the
Professor A. I. Hordvik (ex officio: General Commission on Neutron Diffraction)
Secretary and Treasurer of the IUCr) Solid State Division,
Department of Chemistry, IM R, Oak Ridge National Laboratory,
University of TromsS, Oak Ridge, TN 37830, USA.
PO Box 953,
N-9001-TromsS, Professor E. D. Stevens (Secretary)
Norway. Chemistry Department,
University of New Orleans,
Professor F. Menzinger New Orleans, LA 70148, USA.
Dipartimento di Fisica,
Universith di Roma II, Professor S. Wakoh
Via Orazio Raimondo, University of Library and Information Science,
1-00173 Roma, Italy. I-2 Kasuga,Tsukuba-Shi 305, Japan.