"KKR-Workshop: New developments, applications, and collaborations"
University of München, February 13-15
Organized by
Hubert Ebert (University Munich, Germany) and Duane D. Johnson (University of Illinois, Urbana-Champaign, USA)
Sponsored by
Psi-k network of the European Science Foundation (ESF) and Materials Computation Center at the Frederick Seitz Material Research Laboratory (University of Illinois, Urbana-Champaign, USA) in collaboration with EU-network Computational Magnetoelectronics CCP9 - Collaborative Computational Project for the Study of the Electronic Structure of Condensed Matter
The goal of the workshop, held from 13th until 15th February 2004 at the University of Munich, was to bring together European and United States researchers developing and applying KKR electronic structure methods; especially to share recent advances and to enhance international collaborations on method and software development. The various contributions (23 oral and 24 poster presentations; 54 participants - see below) indeed reflected the many recent developments and their applications in a number of different fields.
The combination of the KKR-method with various many-body techniques have been discussed and demonstrated by several contributions. This included the dynamical mean field theory (DMFT) techniques (Chioncel, Minar), the Self-interaction Corrections (SIC) approach (Lders, Daene), the Optimized Potential Method (OPM) (Akai) and - as a very new approach - the use of the dynamical CPA (Gyorffy).
Closely connected with an improved treatment of many-body effects are corresponding developments and applications in the field of electron spectroscopy. Contributions in this field dealt with photo emission (Minar, Szajek, Winter), X-ray absorption (Giorgetti, Sipr), Appearance Potential Spectroscopy (Braun), optical properties (Perlov), positron annihilation (Benea), and magnetic Compton-scattering (Major).
A very appealing property of the KKR method is its applicability to systems without three dimensional periodicity. This feature has been exploited in contributions dealing with thin films (Udvardi), surfaces (Winter), intefaces (Yavorsky), nanowires (Lazarovits, Ujfalussy), nanocontacts (Mertig, Szunyogh), impurities (Jezierski), and inclusions (Eisenbach) in bulk systems, supported clusters and nanostructures (Stepanyuk, Niebergall) and free clusters (Sipr, Bornemann).
Concerning the treatment of disordered alloys the combination of the KKR-method with the Coherent Potential Approximation (KKR-CPA) has been very successful in the past. This was demonstrated by work presented on electronic and thermodynamic properties of alloys (Johnson) and ordering phenomena in metallic alloys (Bruno). Another application of the KKR-CPA was devoted to the investigation of magnetic properties at finite temperature within the disordered local moment (DLM) model (Staunton). This contribution in particular dealt with the influence of spin-orbit coupling. Another new technical development concerning the treatment of disorder is the non-local CPA (Rowlands), that allows to go in a systematic way beyond the single-site CPA.
The great flexibility of the KKR-method stems from the fact that it gives directly access to the electronic Green's function. This feature is exploited in particular when dealing with the transport properties of nanostructures (Mavropoulos, Szunyogh, Papanikolaou, Bagrets, Mertig, Popescu). Another example for this is a recently developed description for the magnetic highfield susceptibility of magnetic alloys (Mankovskyy).
A rather large number of contributions (including applications of other band structure methods) werh dealing with materials interesting for applications in magneto-electronics. Besides the magnetic-nano-structure mentioned above, most interest was on diluted magnetic semiconductors (Akai, Dederichs, Sanyal) and half-metallic systems (Temmerman, Szotek).
According to the primary aim of the workshop some few contributions were selected as key lectures that deal with technical developments, as the implementation of the Lloyd formula (Zeller) and the data exchange between different program packages making use of XML (Schulthess), and also to review the activities of the non-European participating groups (USA: Stocks; Japan: Akai). In line with this, an adequate amount of time had been devoted to discussions on common future developments and collaborations. One of the resulting arrangements of these discussions is to have the next KKR-workshop in Bristol in 2006.
Hubert Ebert Duane D. Johnson
More details may be found in newsletter 62 from page 20.