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Welcome Statement
The physical reality of our world is often complicated and difficult to unveil. Fortunately now it can be efficiently simulated in a computer. In fact in many situations, when experiments are too complicated, too expensive or too difficult to interpret, or when there are no experiments at all, it is useful to perform computational experiments. In these one solves with a computer the fundamental laws governing the physical phenomena. Such an approach has become a successful strategy in materials science and device designing and it is now invading other scientific areas such as biology and in a future medicine. However "teaching" to a computer how to solve a problem is complicated in itself. The research program of the Computational Spintronics Group at Trinity College Dublin aims at developing a series of sophisticated methods for simulating small-scale devices, in particular including magnetic elements. These allow us to predict their properties ahead of experiments and to tackle challenging problems with a potential for generating novel revolutionary devices. Such devices are then pursued experimentally by our colleagues at the Center for Research on Adaptive Nanostructures and Nanodevices (CRANN).
Stefano Sanvito
Latest News and Research Highlights
28 Novemeber 2011
New Variational version of SIC
A new variational form for the atomic self-interaction correction method has been recently published [Phys. Rev. B 84, 195127 (2011)]. This extends on the previous non-variational version and allows one to calculate forces and geometries for solids and molecules. We have implemented such a scheme both in Siesta and a plane-wave code and the same method is available together quantum transport in Smeagol. The paper is a collaboration with University of Cagliari (Italy) within the EU project ATHENA.
29 August 2011
Current induced forces in Smeagol
The possibility of calculating current induced forces is now a reality in Smeagol. A new work, published in Phys. Rev. B this week [Phys. Rev. B 84, 085445 (2011)], demonstrates the implementation of a current induced forces algorithm in Smeagol. As a demonstration we have evaluated the migration barriers for Si adatoms on C-nanotubes and demonstrated that Si can be moved efficiently at relatively moderate current densities. Problems such as electron-migration can now be tackled with first principles methods.
23 May 2011
New Review article on Molecular Spintronics
A new review article on Molecular Spintronics has been published today in Chemical Society Reviews. Check out Chem. Soc. Rev., 2011, 40, 3336-3355 at our publication list page.
5 April 2011
New Computational Spintronics Blog
As a quick vehicle to share information and opinions on science and what is around it, visit our new blog at ..... see below
25 February 2011
Computational Spintronics Facebook page now open
We have now a facebook page and group where you can follow our activity. Please join in a keep yourself up to date with the latest news from the Spintronics world.
18 February 2011
The ACRAB project has officially opened
A new alliance has been established between the Computational Spintronics group and the group of Prof. Udo Schwingenschlögl at the King Abdullah University of Science and Technology (KAUST). This is the ACRAB project. ACRAB is the arab name of a star in the head of the Scorpio Constellation, and accordingly to traditional astrology it is credited with giving the ability to do research, and especially research into things of a particularly secret and hidden nature. This is precisely what the ACRAB alliance is about.The ACRAB project will develop a range of theoretical/computational techniques to study electron transport in complex materials systems. In particular we will tackle problems connected to large scale simulations, to strong electron correlation and to the interaction with a biological environment. Direct applications to our methods will be in the development of organic solar cells, of nanoscale transistors and of bio-sensors. All these are at the heart of the scientific missions of both TCD and KAUST. The new developments will be merged in the Smeagol code, Dublin's premier computational tool. Smeagol will significantly increase its capabilities and will meet the requirement to become the ultimate simulation package for nanoscience. The Dublin team, in addition to Prof. Sanvito, will be headed by Dr. Ivan Rungger, the main Smeagol developer, by Dr. Clotilde Cucinotta and by a newly hired PhD student (Amaury Melo Souza). This will be mirrored by the KAUST team at present comprising Prof. Schwingenschlögl, Dr. Konstantinos Gkionis, Joshua Obodo and Chengjun Jin.The project will also bring two additional alliances. It will establish a relation between the Center for Research of Adaptive Nanostructure and Nanodevices (CRANN) at TCD and KAUST, and also will bring together researchers from the Trinity Center for High Performance Computing (TCHPC) and the KAUST supercomputer center.
17 September 2010
Electron transport in dry DNA revealed
The bias-dependent transport properties of short poly(G)-poly(C) A-DNA strands attached to Au electrodes are investigated with first-principles electronic-transport methods (Smeagol). We show that electronic wave-function localization, induced either by the native electrical dipole and/or by the electrostatic disorder originating from the first few water solvation layers, drastically suppresses the magnitude of the elastic conductance of A-DNA oligonucleotides. We then argue that electron transport through DNA is the result of sequence-specific short-range tunneling across a few bases combined with general diffusive/inelastic processes.
16 September 2009
The Electrostatic Spin-Crossover Effect
The magnetic configuration of a nanostructure can be altered by an external magnetic field, by spin-transfer torque or via its magneto-elastic response. Now there is an alternative route, namely the possibility of switching the sign of the exchange coupling between two magnetic centers by mean of an electric potential. This general effect, that we name "electrostatic spin crossover", occurs in insulating molecules with super-exchange magnetic interaction and inversion symmetry breaking. Taking as an example a family of di-cobaltocene-based molecules we have demonstrated that the critical fields for switching, calculated from first principles, are of the order of one V/nm and can be achieved in two-terminal devices. More crucially such critical fields can be engineered with an appropriate choice of substituents to add to the basic di-cobaltocene unit. This suggests that an easy chemical strategy for the synthesis of suitable molecules is possible.
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