Psi-k - Ab initio (from electronic structure) calculation of complex processes in materials


Ab-Initio Electron-Excitations Theory: Towards Systems of Biological Interest

From: Pablo Garcia-Gonzalez []
Sent: 14 September 2002 22:25
To:
Subject: Application for financial support form ESF-Ψk Programme

Dear Prof. Temmerman:

On behalf of the organising committee, I am pleased to send you the enclosed proposal for a workshop entitled "Ab-Initio Electron-Excitations Theory: Towards Systems of Biological Interest" to be considered for financial support from the Ψk Programme.

If you have any query, please do not hesitate to contact the corresponding organiser at the address indicated below.

Yours faithfully

Dr. Pablo Garcia-Gonzalez ()
Departamento de Fisica de la Materia Condensada,
Universidad Autonoma de Madrid, E-28049 Cantoblanco, Spain
Phone: +34 91 397-3805, Fax: +34 91 397-3961

AB-INITIO ELECTRON-EXCITATIONS THEORY:
TOWARDS SYSTEMS OF BIOLOGICAL INTEREST
PROPOSAL FOR A FOUR-DAY WORKSHOP AT DIPC (San Sebastian, Spain)
APPLICATION FOR FINANCIAL SUPPORT FROM THE ESF Ψk PROGRAMME


1. MAIN INFORMATION:

WORKSHOP TITLE:
Ab-Initio Electron-Excitations Theory: Towards Systems of Biological Interest

PURPOSE:
The aim of this four-day workshop is to assess the present status of theoretical approaches to the study of spectroscopic properties of real materials, and explore their capability for applications in further systems with technological and biological interest. Due to the different methods used to tackle this problem (Many-Body Theory, Time-Dependent DFT, configuration interaction, semi-empirical approaches), this workshop is also intended as a way to promote links among scientist coming from different communities working on excited states.

ORGANISERS:
Pablo Garcia-Gonzalez (corresponding organiser)
Departamento de Fisica de la Materia Condensada,
Universidad Autonoma de Madrid, E-28049 Cantoblanco, Spain
Email:
Phone: +34 91 397-3805, Fax: +34 91 397-3961

Maurizia Palummo
Dipartimento di Fisica, Universita di Roma Tor Vergata,
Via della Ricerca Scientifica 1, 00133 Roma, Italy
Email:
Phone: +39 06 7259-4548, Fax: +39 06 2023507

Olivia Pulci
Dipartimento di Fisica, Universita di Roma Tor Vergata,
Via della Ricerca Scientifica 1, 00133 Roma, Italy
Email:
Phone: +39 06 7259-4503, Fax: +39 06 2023507

Arno Schindlmayr
Fritz-Haber-Institut der Max-Planck-Gesellschaft,
Faradayweg 4--6, 14195 Berlin-Dahlem, Germany
Email:
Phone: +49 30 8413-4845, Fax: +49 30 8413-4920

Nathalie Vast
Laboratoire des Solides Irradies, Ecole Polytechnique,
91128 Palaiseau, France
Email:
Phone: +33 1 6933-3825, Fax: +33 1 6933-3022


2. SCIENTIFIC CONTENT AND MOTIVATION
While structural properties of materials are mainly determined by the static electronic ground state, the response to external probes in modern non-destructive spectroscopies must be explained in terms of dynamic excitations. Thus, the knowledge of excited states is essential not only for its fundamental importance in Condensed Matter Physics, but also for the impact in practical applications like the design of new materials with technological or medical interest.
The theoretical foundations of this field are well established, and have been accompanied with physically well-motivated approximations suitable for ab-initio calculations in real materials. Namely, in the context of many-body-perturbation-theory (MBPT), Hedin's GW approximation [1] has been highly successful in predicting single-particle spectra and quasiparticle lifetimes [2]. It is also used as a first step in the theoretical many-body study of two-particle excitations (Bethe-Salpeter equation), which is required to obtain a correct description of photoabsorption spectra [3,4]. On the other hand, time-dependent density functional theory (TDDFT) [5] is an alternative to calculate optical spectra with neutral excitations, with the important advantage of being more amenable for practical simplifications than MBPT-based schemes [4].
These methods have been extensively checked in a number of systems, ranging from simple atoms to systems with prospective technological interest. Presently, they provide reliable interpretations of experiments such as photoemission, photoabsorption, electron-energy-loss spectroscopy, X-ray absorption or scanning-tunneling microscopy [2,4]. In addition, sophisticated efficient numerical algorithms have been developed during the last years [6,7]. Nonetheless, the current status of ab-initio methods to determine excited state properties contrasts significantly with the level reached by the Kohn-Sham (KS) method (using the local density or the generalized gradient approximations), which is now a standard tool in research and development. Furthermore, although KS-DFT should be restricted to ground-state calculations, it has been used as a practical way to study, for instance, transport phenomena or band-structures in complex biostructures [8].
In the last few years, there has been a significant growth of the complexity of those systems whose excited-state properties have been studied using ab-initio techniques. Presently, systems like quantum dots, nanocrystals, and conjugated polymers are accessible using truly ab-initio methods [4,7,9]. Thus, the progress made in this field has already provided the basis for its application to more complex systems with biological interest. This calls for a broad-scope meeting to explore such a possibility and promote interdisciplinary dialogue. Being this the main motivation of this workshop, we are aware that steps in this direction require the assessment of the theoretical approximations themselves and of the feasibility of the existing numerical codes to tackle these more complicated phenomena. Therefore, discussions about state of the art implementations of ab-initio methods in condensed matter and quantum chemistry will have a prominent role in this meeting. On the other hand, a representative part of the workshop will be devoted to presentations on the study of dynamical properties of organic and biology-oriented systems which use simpler techniques, like semi-empirical tight-binding approaches or KS-DFT [8,10]. Thus, we expect to promote the exchange of ideas among scientists belonging to different communities and motivate the application of ab-initio methods to systems with immediate interest beyond basic research. At this respect, interaction with experimental groups is a must and with this idea borne in mind, we have also included several experimentalists among the invited speakers. Thanks to the applicative character of this workshop, we aim to develop a strong interaction with groups using up-to-date spectroscopic techniques devoted to the study of complex and biological systems.
The aforementioned progress in theoretical approaches to electron excitations has been reflected on the increasing impact of previous workshops on 'Excited Electrons in Molecules, Solids and Atoms' (Lyon,1997), 'Spectroscopy of Electronic Excitations in Materials' (Valladolid,1998), 'Calculation of Electronic Excitations in Finite and Infinite Systems' (Lyon, 1999) and 'Excited States and Electronic Spectra' (Lyon, 2000), all organised by Giovanni Onida, Angel Rubio, and Lucia Reining. These workshops have had an acknowledged contribution to the establishment of a very strong community of scientists interested on applications of MBPT and/or TDDFT in Condensed-Matter Physics. This series will continue with the forthcoming Ψk/CECAM meeting on 'Ab-initio Theoretical Approaches to the Electronic Structure and Optical Spectra of Materials' (Lyon, 2002). As described, the 2003 meeting has a broader scope, but we want to keep the overall format of preceding conferences: informal general style, ample time devoted to discussions and round-tables, and preference for contributions by young scientist. Since the main goal of this workshop is the exploration of future applications and prospects of ab-initio techniques, we are confident that a friendly atmosphere will help in the achievement of such an objective.

References:
[1] L. Hedin, Phys. Rev. 139, 796 (1965)
[2] F. Aryasetiawan and O. Gunnarsson, Rep. Prog. Phys. 61, 3 (1998); W.G. Aulbur et al., Solid State Physics (Academic Press, Orlando, 2000) Vol. 54, p 1; P.M. Echenique et al., Chem. Phys. 251,1 (2000)
[3] S. Albrecht et al., Phys. Rev. Lett. 80, 4510 (1998); L.X. Benedict et al., Phys. Rev. Lett. 80, 4514 (1998); M. Rholfing and S.G. Louie, Phys. Rev. Lett. 81, 2312 (1998)
[4] G. Onida, L. Reining, and A. Rubio, Rev. Mod. Phys. 74, 601 (2002)
[5] E. Runge and E.K.U. Gross, Phys. Rev. Lett. 52, 997 (1984).
[6] F. Aryasetiawan and O. Gunnarson, Phys. Rev. B 49, 16214 (1994); L. Steinbeck et al., Comput. Phys. Commun. 125, 105 (2000) B. Arnoud and M. Aluaini, Phys. Rev. B 62, 4464 (2000)
[7] I. Vasiliev et al., Phys. Rev. B 65, 115416 (2002)
[8] P.J. de Pablo et al., Phys. Rev. Lett. 85, 4992 (2000) M. Cote, et al., Phys. Rev. B 63, 125207 (2001) R. di Felice et al., Phys. Rev. B 65, 145104 (2002) F.L. Gervasio et al., Phys. Rev. Lett. 89, 108102 (2002)
[9] A. Franceschetti et al., Phys. Rev. B 60, 1819 (1999); M. Rohlfing and S.G. Louie, Phys. Rev. Lett. 82, 1959 (1999); J.-W. van der Horst et al., Phys. Rev. B 66, 035206 (2002); A. Ruini et al., Phys. Rev. Lett. 88, 206403 (2002)
[10] T.A. Niehaus et al., Phys. Rev. B 63, 085108 (2001).


3. TENTATIVE LIST OF INVITED SPEAKERS

4. PARTICIPANTS

We primarily intend to invite physicists representing research groups in state of the art applications to biology as well as in many-body theory and time-dependent DFT. However there will be an important presence of invited speakers who have a well recognized experience on other theoretical approaches or are experts on spectroscopies that are currently used in the experimental characterisation of excited-state properties. On the other hand, the call for participation will be mainly directed to scientists specialized on computational physics and quantum chemistry, but the achievement of the objectives above described also requires to emphasize more conceptual aspects of the theory. Accordingly, we will ask for cross-disciplinary contributions: ranging from fundamental studies to semi-empirical approaches to investigate very complex phenomena. We will limit the number of participants to less than 90, in order to ensure a maximum interaction between scientist belonging to different communities, intense participation in the round-table sessions and after each talk, and a live-discussion environment extended to breaks and meals. Attendance of graduate students and postdocs will be strongly encouraged through the inclusion of short contributed talks and poster sessions with brief oral introductions. Furthermore, we will suggest to Ph.D. students who had presented an outstanding poster contribution to convert it into a short talk.

5. TUTORIAL ELEMENTS AND ATTRACTION OF NEW RESEARCHERS

We recognise the important training aspect of the workshop specially for newcomers to the field. Thus, two keynote scientists (in principle L. Reining and R.W. Godby) will be invited to give a review seminar on the state of the art of many-body- and TDDFT-based applications. These review seminars have been planned not only for their tutorial impact, but also to stimulate the interest of researchers not familiarized with ab-initio calculations.
Poster sessions, chaired by an invited speaker, include a short oral introduction. They are designed to emphasize the work of individual young researches and provide more time for discussions, thus giving them the opportunity to enrich their scientific contacts with recognized senior researchers.
Due to the emphasis on high-level research, we do not plan specific tutorials on excited-state calculations. Nonetheless, the ample break time between sessions will help to all students and postdocs to share their current research with senior scientists. Finally, the heads of research groups will be invited to advertise job and fellowship opportunities as well as other relevant conferences on their respective fields of interest.

6. FINANCIAL INFORMATION

We estimate a conference cost of 35,000 euro. That includes all the expenses of invited speakers, bursaries for selected young scientist, and additional costs like stationery, publicity, coffee breaks, or abstract books. Donostia International Physics Center will provide its main conference room and all the necessary equipment, so the related expenses are not included in the above estimation. All the funding from the ESF Ψk Programme will be used to provide financial support for graduate students and postdocs and thus encourage their active participation. Only young European researches presenting a main author contribution will be eligible for this financial support. We hope to offer 17 bursaries of 550 euro (280 for living allowance plus 270 for travel expenses). Therefore we apply for a total amount of 9350 euro. The rest of the estimated cost is expected to be financed by conference fees, the Spanish Ministry of Science and Technology, the University of the Basque Country, and the Autonoma University of Madrid. We will explore the possibility of further sponsoring from private non-profit-making institutions.

7. LOCATION

The workshop will be hosted by:
Donostia International Physics Center (DIPC);
Paseo Manuel de Lardizabal 4, 20018 Donostia/San Sebastain, Spain.
The tentative dates of this four-day workshop are:
21 (Sunday) - 24 (Wednesday) September 2003