Teori för fononexcitationer i substitutionellt oordnade legeringar
Tidsperiod: 2012-01-01 till 2014-12-31
Projektledare: Biplab Sanyal
Medarbetare: Olle Eriksson, Subhradip Ghosh
Budget: 719 000 SEK
The study of elementary excitations (electrons, phonons,magnons) in complex materials having substitutional disorder is one of the emerging areas in computational materials science research as disorder is an important control parameter to tailor materials with target properties. Specifically, phonon spectra are essential for thermodynamic properties and hence phase diagrams. However, first principles calculation of phonon spectra in disordered alloys is a challenging problem due to difficulties in computing the inter-atomic interactions in a random environment. In this proposal, we aim to devise a unique formalism for lattice dynamics in disordered alloys combining first-principles electronic structure methods, physically realistic models of chemical disorder and an analytic mean-field based method for configuration averaging. The effects of short-range order, partial disorder and temperature on the vibrational properties will be studied to interpret the experimental results available for binary metallic alloys, multi-component shape memory alloys, multi-component semiconductor alloys, partially disordered perovskite ferroelectrics and doped multiferroic materials. One of the key objectives will be to build up a database of inter-atomic force constants to serve as a ready reference for the community. This collaboration between Uppsala University and IIT, Guwahati, India involves exchange visits, organization of schools to train young scholars and joint publications.