SIG-02 Activity Reports 2002-2004

Report 2004-2005

In 2004 two major meetings were organised with the involvement of SIG #2.

  1. ECM-22; Budapest, 26-31 August 2004. A Plenary lecture was given by Prof. U. Pietsch on: gElectron density determinations under non-ambient conditionsh. Also two micro-symposia were organised: hElectronic effects in molecular interactionsh, jointly with SIG #7, and gElectron densities in complex systems and under non-ambient conditionsh. Both symposia had prominent speakers and were very well attended, just like the plenary lecture, showing the healthy interest in density research in Europe.
  2. The Gordon Research Conference (GRC) on Electron distribution and chemical bonding. The Chemical Bond : densities and dynamics; Mount Holyoke College, MA, USA, July 4-9, 2004. Chair: John Spence (USA); co-chair: C. Gatti (Italy). This GRC is along with the Sagamore conference one of the major activities of the Charge, Spin and Momentum Densities community and it is traditionally focussed more on the Charge Density aspects and on the chemical features derived thereof. The conference included sessions on thermoelectric materials, electron diffraction, resonant scattering, electron density topology, progresses in charge density refinement, time-resolved crystallography, surfaces, in addition to two exciting poster sessions, each one lasting for two whole days. The conference has been well attended (96 delegates), with large participation from young scientists (55% below 40’s) and with prominent attendance from SIG-2, with 55% of delegates and 58% of the invited speakers coming from Europe. Carlo Gatti (Italy) and Dylan Jayatilaka (Australia) have been appointed as the next chair and co-chair, respectively, for the upcoming 2007 GRC.

SIG #2 is involved in or in charge of organising various meetings in 2005 and 2006.

  • Members of our SIG, as members or Chair (Claude Lecomte, Nancy) of the IUCr commission on Charge Spin and Momentum Densities, have been highly involved with the organization of the scientific activities in the SIG area for the XX IUCr congress (Florence,August 23-31, 2005). Three micro-symposia (MS), with four out of the six appointed chairs coming from Europe, have been planned plus one keynote lecture:
  • MS 34 : Advances in Computational Methods for Electron Density Studies (Chairs: Louis Farrugia and Tibor Koritsanzky)
  • MS 49 :Charge, Spin and Momentum Densities in Material Science (Chairs: John Spence, Bo B. Iversen)
  • MS 63 : Chemical Insights from Electron Density Studies and Wavefunctions (Chairs: Nour Eddine Ghermani, Peter Blaha)
  • A keynote lecture on Electrostatic and related properties from accurate charge density analysis will be delivered by Marck Spackman (Perth, Australia), with Vladimir Tsirelson (Moscow, Russia) acting as Chair.
  • The fourth European Charge Density Meeting will be held in Brandenburg/Havel 24.- 29 January 2006 and organized by Ulli Pietsch and his group from University of Postdam, Germany. The international conference will be partially shared with annual report meeting of German Priority Program “Experimental electron densities as key tool for the understanding of chemical interactions” (see below).In summary we expect 100 to 120 participants both experienced European scientists and students and post-docs. The conference will deal with new trends in charge density analysis and interpretation, including a tutorial program for young students and young scientist.
  • Sagamore XV, 13-18 August 2006. The Sagamore conference is one of the major conferences of the Charge, Spin and Momentum Density Community. The 2006 meeting is organised by Prof. Malcolm Cooper and will be held at Bosworth Hall Hotel in Leicestershire, UK. The conference will cover a broad range of topics of interest to the physics, chemistry and crystallographic community addressed by charge, spin and momentum density studies. For further information see www.sagamore2006.com
  • ECM-23 Leuven, 6-11 August 2006. The chair of SIG#2 is involved in the early stages of putting together the scientific program.

Other activities

In April 2005 about 30 groups received funding by German Funding Agency (DFG) after approval of the new scientific priority program (SPP1178) “Experimental electron densities as key tool to understand chemical interaction”. In addition to mainly German groups the funding includes one project of an non-German proposer (Tibor Koricansky). The total duration of SPP is scheduled for 6 years where each proposal becomes reviewed every 2 years. The major activity if SPP is an annual report meetings (see above). (http://www.dfg-spp1178.de/).

 

Report 2003-2004

Scientific Meetings

In 2003 three closely spaced meetings were organised with the involvement of SIG #2.

  1. The Third European Charge Density Meeting, ECDM-III, and “The European Science Foundation Exploratory Workshop”, Sandbjer, Denmark June 24-29. This meeting was already reported upon in the 2003 report.
  2. Sagamore XIV, Broome Australia, August 13-18. This meeting was organised in conjunction with the AsCA’03/Crystal-23 conference (Aug 10-13) and the Biological Structure workshop (Aug 13-15). The Sagamore conference is one of the major conferences of the Charge, spin and momentum density community. The conference was very well attended by people from the different continents. Members of the ECA SIG #2 were heavily involved in the scientific program committee, the organisation, as well as in the scientific presentations. The conference was a major success.
  3. ECM-21 Durban, 25-28 August 2003. Two mirco symposia were organised by SIG #2 during the ECM-21 meeting: “The synergy of experiment and theory in studies of charge, spin and momentum densities”, chaired by P. Becker and “Impact of charge and spin density studies on molecular sciences” chaired by F.K. Larsen. A third micro symposium was directly related to the field covered by this SIG: “High resolution x-ray diffraction at new European SR sources” chaired by M.V. Kovalchuk.

In 2004 SIG #2 is involved in the ECM-22 meeting, Budapest, August 26-31. One micro-symposium is organised by SIG #2: “Electron densities in complex systems and under non-ambient conditions” (H. Graafsma and M. Souhassou). One joint session is organised together with SIG #7, “Electronic Effects in Molecular Interactions” (Paola Gilli and Teresa Borowiak). One plenary lecture will be given by U. Pietsch on: “Electron density determinations under non-ambient conditions”.

People from SIG #2 are also heavily involved in the organisation of the Gordon Research Conference on Electron Distribution & Chemical Bonding, July 4-9, 2004, Mount Holyoke USA. C. Gatti, the secretary of SIG #2, is the vice chairman of this meeting. Since Charge density research is very strong in Europe, there will be numerous members of SIG #2 participating in and contributing to this GRC.

Other activities

Following the ECDM-III in June 2003, F. Larsen is editing a special issue of Acta Crystallographica A on charge density. The papers submitted to this issue are in the advanced stage of refereeing.

 

Report 2002-2003

 

This SIG has been particularly active in the last year. The most important activities are listed here, in chronological order, and commented at length below.

  1. Micro symposia (MSs) organization and lectures at XIX IUCr congress (Geneve, Switzerland, August 6-15, 2002).
  2. Participation (as organizers, teachers and attendants) to the Workshop on Advanced Methods in X-ray Diffraction Analysis. The XD Programming package. Buffalo, USA, (May 12-17, 2003).
  3. Organization of 3 rd European Charge Density Meeting (ECDM-III), Sandbjerg Estate, Denmark, 24-26 June 2003.
  4. Organization of the European Science Foundation (ESF) Physical and Engineering Sciences (PESC) Exploratory Workshop on New Information from Modern Charge Density Studies, convened by Bo Brummersted Iversen and Finn Krebs Larsen in Sandbjerg Estate, Denmark, 27-29 June 2003.
  5. Planning for ECDM-IV
  6. First steps towards the submission of a proposal for an ESF Network related to CSMD scientific activity.
  7. Participation to the scientific committee of the XIV Sagamore Conference on Charge Spin and Momentum Densities, Broome, Australia, August 13-18, 2003.
  8. Organization of MSs at ECM-21, Durban, South Africa, August 24-29, 2003.

XIX IUCr congress: members of this SIG were in charge of the organization of 3 MSs. Namely, M9 :” X-ray and Neutron Magnetic Crystallography “, chairpersons: F. Tasset and M. Costa; M28 ” Molecular and Crystal Properties from Charge and Spin Densities “, chairpersons: C. Gatti and M. Cooper, scientific report in IUCr Newsletter, vol. 10,3, 8-9 (2002); M41 ” Quantum Crystallography: Electronic Correlation and Bonding “, chairpersons: G. Loupias and S. Manninen. Seven out of 15 lecturers of these MS were European. In M28, the first lecture ” From polypeptides to protein properties using a charge density approach ” was delivered by the ECA President, Prof. Claude Lecomte.

Participation to each of these MS was numerically relevant (about 200-250 scientists). Other members of this SIG have been strongly involved in organizing MSs or giving lectures at MSs other than those directly “sponsored” by the CSMD commission of IUCr. For instance, M21 on “Low temperature crystallography: methodology and Application”, chaired by A. Goeta and R. Destro and with lectures by F.K. Larsen (” Cryo-crystallography. The lower the temperature, the better?”) and P. Macchi ( Low temperature: a “non innocent” must for accurate electron density studies “). The two keynote lectures delivered by SIG members, V. Tsirelson (” New frontiers in Charge Density “) and W. Weyrich (” Chemical Bonding as Electronic Coherence “, report on Iucr Newsletter, vol. 10,4, 14, 2002) further testify the vitality and scientific relevance of European scientists in this field.

Workshop on Advanced Methods in X-ray Diffraction Analysis. The XD Programming package. This workshop ( http://harker.chem.buffalo.edu/group/announcement/xd.html ) , sponsored by IUCr was held at Buffalo University in may 2003. The workshop was aimed at presenting a new release of the XD program for X-ray charge density analysis. This release includes interesting features such as new relativistic wave functions for atoms and ions, full topological analysis due to incorporation of topXD in XD, evaluation of atomic and/or molecular multipole moments with several crystal space partitions, a Window version of XD, etc. The workshop enjoyed a large attendance, about 45 young and less young scientists from everywhere in the world, in particular from Europe, and met a great success. The schedule was tight with one main lecture and 3-4 short lectures every morning and the afternoon session fully dedicated to practical tutorials, with attendants divided in two groups, beginners and advanced.

Contribution from members of this SIG was relevant. Not only as authors (L. Farrugia, C. Gatti, Piero Macchi, P. Mallinson) of the new XD features, but also as organizers (P. Macchi) and teachers (L. Farrugia, C. Gatti, Piero Macchi, P. Mallinson) of this workshop.

ECDM-III and ESF PESC Exploratory Workshop on New Information from Modern Charge Density Studies. ( http://www.chem.au.dk/~ECDM-III/index.html ). The Third European Charge Density Meeting, organized by F.K. Larsen (co-chairman of this SIG), Bo Brummerstedt Iversen and Charlotte Secher, and sponsored by the IUCr has really been the fourth in a series of meeting (Durham 1995, Nancy 1996, Barcellona-Sitges 1999) aimed at advancing the craft of electron density determination and interpretation for use in chemical, physical and biological sciences. The organizers decided to try to actively reach out towards other branches of science and applied for funds at the ESF to run in connection with ECDM-III, an Exploratory Workshop with the theme: New Information from Modern Charge Density Studies. The ESF accepted this proposal and granted the necessary financial means to invite about twenty top scientists to come and lecture, and to engage in stimulating interdisciplinary discussions. This made it possible to have a relevant number of the international leaders of the field attending both meetings who ran one after the other, with most of the participants (about 65 for each meeting) in common. They have been very lively, well attended meetings, with lot of discussion, both in and outside the lecture hall. Participants were from 16 different countries, mostly from Europe but also from USA, Japan, Taiwan and Australia. The Sandbjerg Estate conference center, owned by the Aarhus University, provided a splendid location for the two meetings, with excellent conference and living quarters facilities.

ECDM-III opened with a session on the Status and future developments in software for experimental charge density studies that gathered practically all the developers of the software (XD, MOLLY-N, MOPRO, InteGriTy, VALRAY, ENIGMA, TONTO, WinXPRO2003) most currently used in charge density studies. We believe that this was really the first time that such a wide and complete presentation was offered. Suggestions and scientific contacts for either improving or linking these different packages have been proposed and formulated.

The workshop had four sessions, one on Chemical Bonding and Reactivity determined by experimental charge density (CD) studies, another on theoretical CD new interpretive methods and calculations, a third on magnetism in relation to CD studies and a final one on frontiers problems, like “in situ” CD studies of photo-induced phenomena, CD studies under high pressure or electric fields, CD studies from high resolution powder diffraction, etc. The workshop was opened by the plenary lecture given by Professor Philip Coppens, who is the eminent expert in the world. It has been closed by a lecture of the ECA president, Prof. Claude Lecomte, pointing the way forward to use CD analysis in biological sciences and backward to warn CD practitioners of the still unresolved problems in the accuracy of CCD data collection and multipolar modeling of systems containing heavy atoms.

This SIG wishes to express his gratitude to ESF and the organizers of the two meetings for making it possible to have such an healthy mix of researchers both from the experimental and theoretical viewpoint, leading to a very good cross-fertilization of new ideas.

Planning for ECDM-IV: during the two meeting held at Sandbjerg Estate conference center, it was decided to continue with the ECDM series of meetings. The German group (responsible Prof. Ulrich Pietsch, Institute of Physics, Postdam) will be in charge of the organization of ECDM-IV. Possible date is 2006.

ESF Network: an ad hoc meeting to plan to apply for a ESF European Network was held during the ESF PESC workshop named above. Representatives from eleven European countries expressed their interest and will act as national coordinators for such an application. The network will be coordinated by C. Lehman (Mulheim an der Ruhr, Germany) and a proposal will be submitted soon to comply with the next deadline. This network, if approved, should facilitate exchange of people and ideas among laboratories and should help in the financial matters concerning the organization of workshops and schools. It would supply the present SIG with new economical and scientific “momentum”.

XIV Sagamore Conference on Charge Spin and Momentum Densities. Several members of this SIG (P. Becker, P. Blaha, C. Gatti, H. Graafsma, A. Gukasov, B.B. Iversen, C. Lecomte, T. Lippman, S. Manninen, F. Tasset) have been actively working in the Scientific Committee of this prestigious international conference. Lecturers from Europe will be particularly numerous. Attendance from Europe is also expected to be significant.

ECM-21: members of this SIG are involved in the organization of two MSs at ECM-21, namely FA4 MS1, The synergy of experiment and theory in studies of charge, spin and momentum densities, chairpersons P. Becker and C. Gatti and FA4 MS2, Impact of charge and spin density studies on molecular sciences, chairpersons F.K. Larsen and N. Ghermani.

Activities listed above, in particular numbers 3 to 6, appear to be certainly in line with the general recommendations for future directions of our SIG. These were already discussed and presented in previous reports. For ease of comparison and judgment, we list again those recommendations below:

  1. Due to specialization, each of the three topics involved in this SIG have a tendency to be discussed separately, and one of our goals is definitely to develop programs combining the three aspects of electron density functions : for example, no program exists that can extract information from combined structure factors and Compton profiles, or from both X Ray and magnetic neutron structure factors.
  2. We think it’s important to promote activities devoted to the study of intermolecular interactions, cohesive forces, in relation to electron density functions. How can the knowledge of electron densities help in predicting chemical behavior of condensed matter is an important topic (where studies of electric potential play a crucial role). Emphasis should be put on the relationship between electron density functions and the behavior of materials under quite general conditions. Strong collaborations with other SIGs, such as the one on Intermolecular effects should be a priority in this respect.
  3. A strong effort needs to be done in order to correlate our experience with other fields of condensed matter research, and workshops could be organized with that aim.
  4. An effort should be devoted to the systematic study of electron density response to applied fields, constraints, electronic excitations. Again collaborations with the SIG on instrumentation is suggested.
  5. Several programs are of general use in our community, both theoretical or devoted to data analysis. It seems interesting to develop, for example through internet, sites where people could exchange their experiences and discuss possible improvements, or needs for new codes…
  6. A site where papers related to our field could be accessed (abstracts, references), even at the pre-print level, seems of interest to many people. In the same spirit, one should have systematic information concerning the most relevant forthcoming meetings.
  7. Through the European community, one should look for possible grants for thesis students, post-docs…
  8. Organization of schools, workshops, sponsoring ECDMs, ECM meetings will be a priority, of course.

P.Becker, F.K.Larsen, C.Gatti

July 21, 2003

Chairman : Pierre BECKER, Professor

SEM/SPMS, Ecole Centrale Paris

Grande Voie des Vignes

92295 CHATENAY MALABRY Cedex, France

tel : 33.1.41.13.13.17 fax : 33.1.41.13.14.37 email : rf.pc1714181052e.mes1714181052@rekc1714181052eb1714181052

Co-Chairman : Finn Krebs LARSEN, Professor

Dept of Chemistry, University of AARHUS

DK-8000 AARHUS C, Denmark

tel : 45.89.42.38.97 fax : 45.86.19.61.99 email : kd.ua1714181052a.ime1714181052k@erk1714181052

Secretary : Carlo GATTI, Doctor

CNR-ISTM, Dept of Physical Chemistry

Via Golgi 19, Milano, 20133, Italy

tel : 39.02. 503.14277 fax : 39.02.503.14300 email : ti.rn1714181052c.mts1714181052i@itt1714181052ag.c1714181052

Report 2001-2002

From Pierre Becker
June 15, 2002

Report on the activities of the Charge, Spin and Momentum Density SIG  

SIG on Charge, Spin and Momentum Density

A major activity of this SIG has been related to the organization of three MS at ECM 20 (Krakow, 25th-31st August 2001), one on “Wavefunctions and Properties from Experiment”, another one on “Experimental Charge Densities” and a third one on “Photo-crystallography”.

MS 1 Wavefunctions and Properties from Experiment
Chair: P. Mallinson (UK); Co-chair: C. Gatti (Italy)
Lecturers : D. Jayatilaka on “Experimental Wavefunctions”; B. Dittrich on the “Group Additivity in Oligopeptides”; P. Becker on “A pseudoatomic decomposition of density matrices: unified approach of charge and momentum densities”; P. Macchi on the “Electron density distribution in Metal Carbonyl Clusters: the role of the Madelung field”; J.M. Raulot on “Electronic structure and bonding in ferroelectric lead perovskites: a comparison to alpha PbO”; P. Starynowicz on “Electron density in phosphoenol-pyruvate”.

MS 2 Experimental Charge Densities
Chair : P. Becker (France); Co-chair: W. Maniukiewicz (Poland)
Lecturers : L. Dobrzynski on “The maximum Entropy Method in Charge Density studies”; B. Guillot on “Multipolar refinement of proteins: tools, methods and applications on Aldose Reductase”; E. Molins on “From the topology of the electron density to the physical properties”; M. Souhassou on the “Study of molecular magnetic interactions by experimental electron density and its topological analysis”; M. Dutheil on the “X-ray Deformation density in B12C3.

MS 3 Photo-crystallography
Chair: T. Luty (Poland); Co-chair: H. Cailleau (France)
Lecturers : A. Rousse on “The bright future of time-resolved crystallography in the subpicosecond timescale; J.R. Helliwell on “The structural chemistry of hydroxymethylbilane synthase”; S. Techert on “Picosecond Photo-Crystallography determines transient structural changes in Organic Chromophores”; Y. Ohashi on “Photo-excited structure of a platinum complex ion; S. Koshihara on “Electronic and Structural Phase Control by Light Excitation.

These three MSs were all very successful and enjoyed a very large and qualified participation (about 100 scientists at each MS), not only from Europe.
A main concern of this SIG was that these MSs could offer examples where the three topics (Charge, Spin and Momentum) involved in the SIG were not discussed separately as it is common practice. A second, not less important aim, was that these MSs could emphasize the very strict relationship existing between CSMD studies, hot questions in materials science and in biological interactions. Overall, we believe that these goals were substantially achieved, especially in some of the lectures and for either one or the other of the goals mentioned above. The MS on Photocrystallography, although not immediately related to the present main activity of this SIG, has disclosed the bright future of time-resolved crystallography in the sub-picosecond timescale. The possibility to observe ultrafast structural rearrangements, making feasible the track of reaction intermediates with a full mapping of transient atomic behavior, and/or the capability of producing localized photo-excited species to trigger macroscopic phase transitions is of large importance for the future activity of this SIG. For instance, the strong electron-electron and electron (spin)-lattice interactions in charge transfer complexes, which are a fascinating topic for CSMD studies, are presumably acting as the driving force in the conversion process of the localized photo-excited species into the macroscopic phase domain. During an informal meeting of the CSMD community, held during ECM20, it has been suggested that a MS title like “Structural and electronic photoinduced effects” could have better reflected the importance of photocrystallography for materials science and could have also attracted a larger and diversified audience to MS 3.

The poster sessions associated to the three MS were also successful, with a large attendance to the 11 presented posters. While the number of posters presented within these MSs was numerically scarce, the increasing use of CSMD analysis in various scientific areas was testified by the not negligible number of lectures and posters presented by the CSMD community in other sessions, like that on Building, Visualization and Modeling, on Perovskite Materials, on Intermolecular Interactions, on Prediction of crystal structures, etc.
The plenary lecture by Claude Lecomte (LCM3B, Nancy, France) on the “New applications in Charge Density Research” showed how the charge density research may be applied to materials science, chemistry, physics, mineralogy and, quite recently, even to biology. This lecture has also emphasized as the 3rd generation synchrotron sources will soon allow charge density determinations under extreme conditions (T,P, electric field, etc.) opening a totally new era for CSMD studies.

Our SIG has been strongly involved with the scientific organization and scientific activity of the 2001 Gordon Research Conference (GRC) on “Electron Distribution and Chemical Bonding” (Mount Holyoke College, South Hadley, MA, July 8-13, 2001) This GRC, which has been chaired by Claude Lecomte, (Nancy, France) and co-chaired by John Spence (Arizona State University, Tempe, USA), was judged very successful by most of the participants and enjoyed a very large participation, with representatives from Europe being the majority. Hot topics like the charge density under extreme conditions, the new perspectives in modeling of X-ray data, the new developments in topological analysis, the degree of complementarity of X-ray and electron diffraction have been discussed at length. New fields like the electron density studies on proteins, the molecular magnetic materials or new emerging techniques like DAFS have been highlighted. New insights in understanding the ubiquitous intermolecular interactions and recent progresses in conceptual Density Functional Theory as a tool for charge density studies have also been presented. Besides chairing, Europeans have been in charge of 11 out of 22 lectures and have been the discussion leaders of 7 out of the 9 sessions. This GRC has also been an important occasion to strengthen the scientific collaboration with SIG on Molecular Interaction and Recognition, with SIG on Extreme Conditions and with the increasingly growing theoretical community of the ELF (Electron Localization Function). On the basis of scientific content, large attendance and general positive judgment, the board of GRC trustees has approved a next GRC on the same subject, to be held in 2004. In the course of the conference, J. Spence has been elected as the chair for the next conference and one member of our SIG, C. Gatti, as the co-chair.

Members of our SIG contributed to the XIth Symposium on Organic Crystal Chemistry (Poznan-Rydzyna, Poland, August 20-24, 2001) and the XIVth Conference on Horizons in Hydrogen Bond Research (Torino, Italy, September 3-7, 2001). In lectures by K. Hermansson, F. K. Larsen, C. Lecomte, P. Macchi and I. Olovsson charge density aspects of hydrogen bonding, including topological analysis and theoretical evaluations were presented and offered significant complement to the spectroscopic description, which resulted in lively discussions. J. Mayers talked about measurement of proton momentum distributions by neutron scattering as a means of finding evidence for quantum tunneling of the proton.

Members of our SIG have also been involved in the organization (C. Gatti) and lectures ( P. Macchi, P. Roversi, C. Flensburg, R. Orlando, C. Gatti, O. Moze) of a full-day short course on “Metodi Sperimentali e teorici di determinazione delle densit? di Carica e di Spin” held within the XXXI Congress (Parma 18-22 September 2001) of the Italian Crystallographic Association. The course enjoyed a numerous, qualified participation and lot of discussions at the end of each lecture. The opening lecture of the Congress was given by C. Lecomte who talked about the combination of ultra high resolution diffraction studies on proteins with deformation densities data-bank and ab-initio theoretical calculations”. This lecture showed how the refinement of proteins with a multipolar ED model in which the multipole populations are transferred from previous peptide studies led to the observation of valence electrons on covalent bonds of the most ordered protein residues.

Our SIG is also currently involved with the scientific activity planned for the next XIX IUCr congress (Geneve 6th-15th August 2002) where we are in charge of the organization of 3 MS (M9 :”X-ray and Neutron Magnetic Crystallography”; M28 “Molecular and Crystal Properties from Charge and Spin Densities”; M41 “Quantum Crystallography: Electronic Correlation and Bonding”) and strongly involved in others MSs, like M21 on “Low temperature crystallography: methodology and Application”. V. Tsirelson will give a plenary lecture on “New frontiers in Charge Density” and W. Weyrich on “Chemical Bonding as Electronic Coherence”.

Finally, thanks to the main effort of Finn Larsen and Bo Iversen (Aarhus, DK), this SIG is organizing the third European Charge Density Meeting, ECDM-III, to be held in the last week of June 2003 at Sandbjerg Estate- Aarhus University Conference Centre. Larsen and Iversen have also submitted a proposal for a PESC Exploratory Workshop on “New Information from Modern Charge Density Studies” which should take place during the ECDM-III. The workshop has the ambitious aim of bringing together scientists from disciplines using charge density (CD) concepts with scientists specialized in measuring, calculating and interpreting the CD. In this way the workshop shall attempt to build common grounds for the many fields drawing on the information contained in the CD, but also, in the bridging process, provide a forum in which new directions for future CD studies can be envisioned. While Europe has indeed a leading position in CD research with many highly active research groups, yet there is relatively little inter-European collaboration. The proposed workshop will provide a forum, which can catalyze collaboration across traditional boundaries (national as well as scientific) and, as a side result, provide new impulse to this SIG.

Several of the activities listed above in this report seem to us to be in line with the general recommendations for future directions of our SIG which were already discussed and presented in the previous reports. For ease of comparison and judgment, we list again those recommendations below:

1. Due to specialization, each of the three topics involved in this SIG have a tendency to be discussed separately, and one of our goals is definitely to develop programs combining the three aspects of electron density functions : for example, no program exists that can extract information from combined structure factors and Compton profiles, or from both X Ray and magnetic neutron structure factors.
2. We think it’s important to promote activities devoted to the study of intermolecular interactions, cohesive forces, in relation to electron density functions. How can the knowledge of electron densities help in predicting chemical behavior of condensed matter is an important topic (where studies of electric potential play a crucial role). Emphasis should be put on the relationship between electron density functions and the behavior of materials under quite general conditions. Strong collaborations with other SIGs, such as the one on Intermolecular effects should be a priority in this respect.
3. A strong effort needs to be done in order to correlate our experience with other fields of condensed matter research, and workshops could be organized with that aim.
4. An effort should be devoted to the systematic study of electron density response to applied fields, constraints, electronic excitations. Again collaborations with the SIG on instrumentation is suggested.
5. Several programs are of general use in our community, both theoretical or devoted to data analysis. It seems interesting to develop, for example through internet, sites where people could exchange their experiences and discuss possible improvements, or needs for new codes…
6. A site where papers related to our field could be accessed (abstracts, references), even at the pre-print level, seems of interest to many people. In the same spirit, one should have systematic information concerning the most relevant forthcoming meetings.
7. Through the European community, one should look for possible grants for thesis students, post-docs…
8. Organization of schools, workshops, sponsoring ECDMs, ECM meetings will be a priority, of course.

P.Becker, F.K.Larsen, C.Gatti