Reikniaðferðir til að spá fyrir um hraða hitaháðra breytinga - verkefni lokið

Fréttatilkynning verkefnisstjóra


The project involved the development of computational methods for identifying the mechanism and estimating the rate of transitions that occur because of thermal fluctuations. 

The focus was on atomic rearrangements as in chemical reactions and diffusion events, but an important aspect of the results is an extension of these techniques to rearrangements of spins as in magnetic storage devices. The challenge in these kinds of calculations is often to find the location of first order saddle points on energy surfaces since the most likely transition mechanism involves displacement of the system from one state to another via such 'mountain passes'. A generalization of this approach was developed where such hopping over mountain passes was used to explore one valley after another to identify the deepest valley. This is essentially the frequently encountered global optimization problem. This algorithm was applied to determine optimal values of parameters in a geological model describing the Laugarnes area in Reykjavík where hot springs have been used over a long period of time. This illustrates how the methods developed in the project can be applied in many contexts, not only to thermally activated transitions.

The results have been implemented in various software packages such as EON (for long time scale simulations of atomic scale systems), LAMMPS (for simulating dynamics of atomic scale systems), Spirit (for simulations of magnetic systems) and ORCA (for calculating electronic wave functions and estimating rates of chemical reactions).

The output of the project are the 17 publications listed above, research presentations at conferences and workshops, and the implementation of the methods in various software packages that are used by a large number of scientists.

Heiti verkefnis: Reikniaðferðir til að spá fyrir um hraða hitaháðra breytinga / Methods for calculating the rate of thermally activated transitions
Verkefnisstjóri: Hannes Jónsson, Háskóla Íslands

Tegund styrks: Verkefnisstyrkur
Styrktímabil: 2013-2015
Fjárhæð styrks: 19,1 millj. kr. alls
Tilvísunarnúmer Rannís: 130595 

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