9. Instytut Podstawowych Problemow Techniki PAN

Computational Materials Science Group (CMSG) will take part in the intergrated computer analysis developed in the framework of the net. The analysis will link the characterisation methods with the FE, MD and other atomistic calculations. CMSG is engaged in the computer analysis concerning the extraction of dislocation maps from the HRTEM images, Phil.Mag. 83 (2003) 231. This original technique is based on the tensorial analysis of lattice incompatibilities. The maps are useful for determination of the atomic structures of dislocation cores. CMSG is also involved in the design and programming of new nonlinear finite element algorithms based on the anisotropic behaviour of crystal structures. This computational method is based on the large deformation approach (finite deformations, second-order elastic and piezoelectric constants dependent n the strain measure applied. These advanced FE algorithms are used for computer simulation of the bending of thin. In the GaN structures the important role plays physical fields coupled with the residual stresses. For example, the invers piezoelectric effect influences on the stress free configuration of thin layers. Therefore the contribution of CMSG will concentrate also on determination of the effect of coupled fields on the residual stresses, band gap shift and self-organization of chemical fluctuations in the investigated semiconductor structures.

The third part of the integrated computer analysis concerns the reconstruction of atomic positions from the FE maps. Solving the respective 3D boundary-value problem the stress equilibrium configurations are obtained. Next, for this configuration, the atomic positions are reconstructed by integration step by step the lattice distortion field. In this way, the atomic structure obtained corresponds to a low energy, deformed atomic structure with misfit dislocations situated in the analysed region. In molecular dynamics this method allows to overcome the problem of the input generation of a (meta-) stable atomic structure containing crystal defects.

CMSG is located in Warsaw and, as a team from the associated state, has not a large experience in the management of European projects. In Poland, 4 projects granted in the years 1993-2003 by the National Committee for Scientific Research were managed by Prof. Pawel Dluzewski. The Group will take part in the organisation and management of the network activity according to the needs.

Scientist in Charge

Prof. Pawel Dluzewski

Phone:(48-22) 826 12 81 ext.184 Fax: (48-22) 826 98 15

email: pdluzew@ippt.gov.pl