*************************************************************** **** **** **** ESF Programme **** **** **** **** RELATIVISTIC EFFECTS IN HEAVY ELEMENT CHEMISTRY **** **** AND PHYSICS **** **** **** *************************************************************** Newsletter No. 30 (October 20, 1998) ______________________________________________________________ Editor: Bernd Hess, hess@pctc.chemie.uni-erlangen.de Tel. 49-9131-8527766 FAX 49-9131-8527736 ______________________________________________________________ The programme 'Relativistic Effects in Heavy-Element Chemistry and Physics' ('REHE') has been initiated by the European Science Foundation in November 1992 and ran for 5 years, i.e. from 1993 through 1997. The programme was intended to strengthen the indicated "field" and to facilitate interactions between European scientists concerned with related topics. Apart from a few activities approved in 1997 and deferred to 1998, the programme expired end of 1997. ================================================================================ --- E D I T O R I A L Dear collegues, for the final report to the European Science Foundation, we have prepared a list of 'papers funded by REHE'. We should like to include in this list all those papers with REHE mentioned in the acknowledgement. This list is now in the www, linked to the REHE newsletter pages at http://pcgate.thch.uni-bonn.de/tc/hess/esf/nl.html ### (yes, still the old www server) I should appreciate very much if you could visit this list and notify me about any papers that should be included. Please, include the number of the corresponding REHE project. Please send this information at your earliest convenience (by email) to hess@uni-bonn.de ### (yes, still the old email address) and send me a reprint for those papers which are not mentioned. ### ### Please send your updates until October 31, 1998; the list as it ### reads at this deadline will be used for the 'final Final Report' ### ------------------------------------------------------------------------- As probably the last official activity of the REHE program there will be a European Research Conference in April 1999. See the announcement below. ------------------------------------------------------------------------- As you might have guessed from the new email address and the new phone/FAX numbers, I have now moved to Erlangen and hold there the chair of Theoretical Chemistry as the successor of Janos Ladik. Please note my new address Prof. Dr. Bernd Artur He{\ss} Lehrstuhl f\"ur Theoretische Chemie Universit\"at Erlangen Egerlandstr. 3 D-91058 Erlangen Tel. : +49-9131-8527766 Fax : +49-9131-8527736 e-mail : hess@pctc.chemie.uni-erlangen.de www : http://www.chemie.uni-erlangen.de/~hess my old email address will still work for quite some time. ------------------------------------------------------------------------- The next newsletter (#31) is not scheduled for a fixed date. We plan to keep the REHE mailing list in the future, but this service will be taken over by the Toulouse group. All REHE newsletters are available on www under URL http://pcgate.thch.uni-bonn.de/tc/hess/esf/nl.html ### and ### http://www.chemie.uni-erlangen.de/~hess/esf/nl.html see also the URL of the European Science Foundation http://www.esf.c-strasbourg.fr ================================================================================ --- 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] The newest version of the RTAM bibliography is in: www.csc.fi/lul/rtam The number of entries is now 9438. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ [communicated by Simon Faas] Report on the visit of Simon Faas to the University of Pisa (Italy) 7-30 November 1997 as a part of a research collaboration with Roy McWeeny, Jaap G. Snijders and Joop H. van Lenthe. This collaboration aims to examine relativistic effects in the computation of chemical importance, such as molecular potential energy surfaces, dissociation energies, and heats of reaction in a Valence Bond context. Such effects are likely to be large for molecules containing heavy atoms, even those in the 3rd row of the periodic table. The target molecules to be considered are halogen compounds of the metal Li, Na, K ... in which the bonding is strongly ionic an problably quite sensitive to the admission of relativistic effects. Our fist aim is to modify the integral package for non-relativistic energy calculations, to include the one-electron relativistic terms in the Hamiltonian at the scalar (i.e. spin free) ZORA (Zeroth Order Regularized Approximation) level. The ZORA or CPD method was originally proposed by Chang, Pelissier and Durand [1] and later generalized by E. van Lenthe, Snijders and Baerends [2] within the framework of molecular DFT. In an Ab Initio context, the ZORA formalism has been tested in numerical calculations on closed shell atoms and it has been shown to recover the most significant relativistic contributions [3]. The scalar ZORA method has already been implemented, within a basis set approximation, in the GAMESS-UK package [4] and test calculations show a very promising behaviour of this Hamiltonian. The Pisa Valence Bond program (VB97) uses a very simular integral package (INTCALC) and most of the necessary extensions have been made by Simon Faas during his visit. In the second stage of the collaboration, the modified integral generator will be assimilated into VB97, which is already operational at the non-relativistic level. The existing program performes a 'seperation' of core and valence electrons and provides for full optimization of the wavefunctions for both core and valence groups, allowing for arbitrary geometry variations: it is thus well able to compute potential energy surfaces, even in the 'difficult' regions where chemical bonds are being broken or formed. Non-relativistic pilot calculations have already been performed on the NaF and KF molecules and it now remains to include the relativistic effects by means of the ZORA modified integral package. It is expected that these preliminary applications will be completed wihtin the next few months and will then be prepared for publication. [1] Ch.Chang, M. Pelissier and Ph. Durand, Phys. Scr. 34 (1986) 394 [2] E. van Lenthe, E.J. Baerends and J.G. Snijders, J. Chem. Phys 101 (1994) 1272 [3] S.Faas, J.G. Snijders, J.H. van Lenthe, E.van Lenthe and E.J. Baerends Chem. Phys. Let. 246 (1995) 632-640 [4] M.F. Guest, J. Kendrick, GAMESS Users Manual, SERC Daresbury Laboratory, CCP1/86/1, 1986: M. Dupuis, D. Spangler and J. Wendoloski, NRCC Software Catalog, Vol. 1, Program No. QG01 (GAMESS), 1980: M.F. Guest, R.J. Harrison, J.H. van Lenthe and L.C.H. van Corler, Theor. Chim. Acta 71 (1987) 117; Note: The CDC version of the GAMESS code was obtained from M. Dupuis in June 1981. Serious development work on the program commenced in January 1982, after conversion to VAX and IBM systems. All sections of the original code have either been extensively modified or replaced in the present GAMESS-UK code. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ [communicated by Paola Belanzoni] Dr.Paola Belanzoni has spent the period 2 February - 2 May 1998 in the Theoretical Chemistry Department at the Free University, Amsterdam, within the REHE fellowship program. She has been working on the following topics: \\ I) A theoretical investigation on the ESR parameters of the blue copper site in PA azurin. \\ Electronic structure DFT calculations on three different models of the copper site of azurin in the oxidised state have been performed by the ADF program and ESR parameters (g and A tensors) have been calculated by employing the companion GATENQ program package. The A-tensor represents a sensitive test of the ability of the method to describe the delocalisation of the unpaired electron over the ligands in the ground and excited states. The active metal site in azurin has five ligands: three bind strongly to copper, the S$_{\gamma}$ atom of cysteine-112 and the N$\delta$ atoms of histidines-46 and -117, forming an NNS plane, the other two ligands interact weakly with copper and occupy the axial positions, the S$\delta$ atom of methionine-121 and the carbonyl oxygen of glycine-45. In the simplest representation of the copper site of azurin only copper(II) and the three strongly bound ligands have been considered: cysteine is replaced by SCH$_3^{-}$ and each histidine by an imidazole group. Two enlarged models have been investigated by adding an axial S(CH$_3$)$_2$ moiety replacing the methionine and a further axial CH$_3$NH$_2$CO group in place of glycine. Inclusion of all the five ligands in the calculations does not significantly change the character of the molecular orbital containing the unpaired electron ( sulfur p$_y$ and copper d$_{xy}$) and the g-tensor values. For all the sites, the unpaired electron remains mainly localised on sulfur and the calculated value of g$_z$ remains too small if compared to the experimental value, while the principal values g$_x$ and g$_y$ are in reasonable agreement. The experimental value of g$_z$ was approached in the calculations when the cysteine was taken to be protonated and represented by SHCH$_3$. The relevance of this observation requires further attention. \\ II) A theoretical study on the hyperfine structure of ligands in the TiF3 complex and its organic analogue CH$_3$. \\ Magnetic coupling parameters (A tensor) calculations have been performed by using the ADF and GATENQ program packages. This work represents a continuation of the investigation on the magnetic coupling parameters for the TiF$_3$ complex already published. The ligand hyperfine splitting has been investigated in greater detail. In the previous work discrepancies existed between spin-restricted and spin-unrestricted results, which moreover both deviated from experiment. The present calculations have solved this issue. In the first place the "experimental" value of the isotropic hyperfine splitting constant has been revised by adopting, on the basis of the calculations, different signs for the experimental parallel and perpendicular principal A values. The signs had originally been assumed to be equal. In the second place the use of large basis sets and unfreezing the 1s core have allowed an accurate description of spin polarization of all occupied shells, which proved to be very important both for the dipolar (2p shell) and especially for the isotropic (1s,2s shells) part of the fluorine hf tensor. Simulations have been run of the ESR spectrum (determined in rare gas matrices) using calculated (spin unrestricted) A tensors. Agreement with experiment is fairly good and lends credibility to the calculated A tensor which differs from the one determined experimentally assuming an axial spin Hamiltonian. The calculated A tensor is not axial. In fact, its principal values do not even reflect the 2p$_{\sigma}$ unpaired electron population at F. Two-center contributions (most of the spin density is at Ti) are found to be the most responsible factor causing the departure from axial (along $z$-axis) symmetry, while also the spin polarization in the occupied F 2p orbitals leads to many counteracting, nonaxial contributions to the dipolar part of the A tensor. The mechanism of the ligand hyperfine coupling in TiF$_3$ has been compared to that acting in the organic analogue CH$_3$. In the Kohn-Sham approach, the spin polarization can be described in simple orbital interaction terms in both the organic and TM systems. As a general conclusion we wish to emphasize that a reliable assessment of the calculated A tensor values requires a careful consideration of the experimental results as well. The "experimental" data may be based on assumptions that prove questionable in the light of the calculations. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ================================================================================ --- 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. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ EUROPEAN RESEARCH CONFERENCES RELATIVISTIC EFFECTS IN HEAVY-ELEMENT CHEMISTRY & PHYSICS Relativistic Quantum Chemistry - Progress and Prospects Aghia Pelaghia, Crete, Greece, 10 -15 April 1999 Chairman: Jaap G. Snijders (Groningen) Vice-Chairman: Ian P. Grant (Oxford) SPEAKERS WILL PROVISIONALLY INCLUDE: M. Barysz (Torun) J. Bieron (Krakow) R. Broer (Groningen) J.M. Dyke (Southhampton) C. Froese Fischer (Nashville) B.A. Heß (Erlangen) E.A. Hinds (Brighton) J. Hrusak (Prague) U. Kaldor (Tel Aviv) C.M. Marian (Bonn) A.-M. Mårtensson-Pendrill (Göteborg) D.M.P. Mingos (London) F.A. Parpia (Poughkeepsie) P. Pyykkö (Helsinki) H. Quiney (Melbourne) S. Rettrup (Copenhagen) A. Rosa (Potenza) T. Saue (Toulouse) H. Schmidbauer (Garching) V. Shabaev (St. Petersburg) G. Soff (Dresden) A. Titov (St. Petersburg) E. van Lenthe (Amsterdam) J. van Lenthe (Utrecht) U. Wahlgren (Stockholm) SCOPE OF THE CONFERENCE Relativistic quantum chemistry has made great progress in the last few years, in which European scientists have made a dominant contribution. The goal of this European Research Conference is to present, review and discuss recent advances in the computational methods developed to treat relativistic effects in atoms, molecules and solids as well as the application of these methods to experimental problems in Spectroscopy and in the description of the chemical bonding in compounds containing Heavy Elements. The meeting will comprise 4 sessions of lectures by invited speakers, devoted to the following areas: * Relativistic Computational Methods. * Relativistic Effects in Spectroscopy. * Relativistic Effects in Heavy Element Chemistry * Relativistic and Quantum Electrodynamic Effects in Atomic Physics. The conference is open to researchers world-wide, whether from industry or academia. Participation will be limited to 100. The emphasis will be on discussion about new developments. There will be a poster session. The Registration Fee covers full board and lodging. Grants will be available for younger scientists, in particular those from less favoured regions in Europe. Deadline for applications: 15 JANUARY 1999 For information & application forms, contact the Head of the EURESCO Unit: Dr. Josip Hendkovic, European Science Foundation, 1 quai Lezay-Marnésia, 67080 Strasbourg Cedex, France. Tel.+33 3 88 76 71 35 Fax.+33 3 88 36 69 87 E-mail: euresco@esf.org on-line information and application on WWW at: http://www-esf-org/euresco Co-sponsored by the European Science Foundation and the Euroconferences Activity of the European Union ================================================================================ --- ADDRESS LIST The REHE address list comprises 195 scientists as of March 24, 1998; the next address list will be provided with newsletter no. 32 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 <<< ================================================================= I am interested in receiving the REHE newsletter NAME ----------------------------------------------------------------- ADDRESS ----------------------------------------------------------------- ----------------------------------------------------------------- TEL ----------------------------------------------------------------- FAX ----------------------------------------------------------------- E-MAIL ----------------------------------------------------------------- MAIN RESEARCH INTERESTS ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ End of REHE Newsletter No. 30