|
|
|
|
|
|
|
|
welcome to the national access programme
a programme of the Tyndall National Institute with funding from SFI |
|
|
Laboratory
feature:
Computational
Modelling Group
This
page is also available in printer friendly format (pdf)
- click here
From atoms... to devices... to
systems
The CMG group at Tyndall develops and applies modelling tools to study materials, devices and systems for advanced microelectronics and nanotechnology.
A variety of methods encompassing the scale of electrons, atoms, processes and systems are used to explain and predict the growth and properties of materials, transport in Si- and nano-devices, binding and diffusion of molecules for imprinting and thermal and mechanical properties of materials and systems.
Facilities available encompass a new 500 core computing cluster, which is available for use by researchers under the National Access
Programme |
|
Examples of CMG work in NAP projects are presented below
Author: Dr. Justin Holmes -
University College Cork
Project title: Understanding the Growth of Bamboo-Structured Carbon Nanotubes on Cu/Mo Catalysts
|
|
CNT growth mechanism must include carbon-metal bond strengths
Fe, Co, Ni of traditional catalysts have the correct C-M bond strength, but Cu, Au do not. Pd is borderline
Type of CNT grown depends on catalyst |
|
|
|
“Ideal” Cu/Mo composite particle binding strengths were predicted from simulations and have been successfully used to grow CNTs experimentally at UCC
Publications
J. A. Larsson et al., Phys. Rev. B 75 (2007) 115419, Nano Lett. 8 (2008) 463
Z. Li, J. A. Larsson, et al "Cu/Mo Nanocomposite Particles as Catalysts for the Growth of Bamboo-Structured Carbon Nanotubes"
Journal of Physical Chemistry - C 112 (2008) 12201 |
Author: Dr. Florence McCarthy -
University College Cork
Project title: Design of novel Ellipticine c-Kit kinase inhibitors
 |
Mutation of a protein leads to formation of a tumor.
If we can inhibit the protein binding site – cancer chemotherapy
Use classical modelling to study binding mechanisms of anti-cancer drugs in collaboration with experiment at ABCRF UCC
Drug Design |
 |
Drug Design
Investigate binding of novel ellipticene drug
Simulations identify novel binding orientation
Fast track the design of more potent and specific anti-cancer drugs |
Publication
D. Thompson, C. Miller, F.O. McCarthy "Computer Simulations Reveal a Novel Nucleotide-type Binding Orientation for Ellipticine-based Anticancer c-kit Kinase Inhibitors"
Biochemistry Journal, 47, 10333-10344 (2008)
Author: Dr. Y.K. Gun’ko -
Trinity College Dublin
Project title: Modelling of Chiral Quantum Dots
At TCD, green/blue-white emitting, optically-active, water-soluble chiral CdS quantum dots of diameters ~5 nm have been prepared.
The QDs are stabilized by the ligand penicillamine, C5H11O2NS, which is chiral, i.e. exists in D- and Lforms. The D- and L-functionalized dots demonstrate a chiral
response when absorbing left-/right-handed circularly-polarised light from 380 nm to 200 nm.
|
|
The
chiral response can come from
- Chiral
nanoparticle core
- Chiral
nanoparticle surface
- Chiral
ligand
|
|
|
|
|
|
|
|
|
Chiral distortion of dot shell due to adsorption of molecules |
The core of the dot remains undistorted |
The electronic states responsible for absorption
Optical response arises from defects, e.g. corners |
Publications
NANO LETT 8 2452-2457 2008 Chiral Shells and Achiral Cores in CdS Quantum Dots S.D. Elliott, M.P. Moloney, Y.K. Gunko
M. P. Moloney, Oral Presentation "Highly Luminescent
Chiral Quantum Dots" IOM3' Nano 2007, Trinity College,
Dublin, 17 December 2007
Author: Dr. Tofail Syed - University of
Limerick
Project title: Oxide Growth in NiTi Shape Memory Alloys
Shape memory alloys, of which NiTi is the most well known, retain a “memory” of their shape when bent and are of potential use as stents in hearts. This arises from formation of a passivating Ti-oxide layer at the surface of the wire, which prevents the passage of Ni from the alloy into the body and provides biocompatibility.
Simulations undertaken at Tyndall were used to understand the initial stages of oxide film growth and why it is preferentially TiO2 that forms, rather than NiO.
 |
Atomic scale model of (110) surface of NiTi, showing front and top views
The surface shows a rumpling so that Ti protrudes from the surface layer |
Adsorb oxygen atom at the surface to interact with Ni, Ti or both Ni and Ti in different orientations
Relax the geometry of the structure
|
 |
In the most stable configuration oxygen (red sphere) bridges two surface Ti and two surface Ni.
These Ti are pulled out of the surface
This will lead to depletion of Ti from the alloy.
Experiment:
• Use Ti from alloy to form TiO2
• Get layer below oxide film that is depleted of Ti
Consistent with modelling
|
Molecular Nanowire Simulation
Molecules tethered to metal contacts (e.g. Gold) are currently being investigated as potential molecular scale electronic devices and to understand the nature of charge transport at these length scales.
In CMG formalisms to compute the resistance of molecular wires have been developed and are being applied.
An example is the case of diamine terminated wires with different wire lengths, for which we have computed the change in resistance with wire length. These finding are consistent with experiment and work is ongoing to understand other effects in molecular scale electronics.
Publication
NANOTECHNOLOGY 18 424010 2007 Tunnelling in alkanes anchored to gold
electrodes via amine end groups G. Fagas, J.C. Greer
Low dimensional structures such as Si nanowires, with diameters in the few nm regime show band gap modulation based on diameter. We have found another mechanism for tuning the band gap of small dimensional Si nanowires, by changing the surface functionalisation. By changing the passivating group at the surface from -H to –OH or NH2, the magnitude of the band gap can be varied by up to 1 eV and the character of the band gap can also be changed.
Si nanowire oriented along (100 direction).
Black spheres show surface passivating groups
Publications
NANO LETT 7 34 2007 Silicon Nanowire Band Gap Modification M. Nolan, S. O'Callaghan, G. Fagas, J.C. Greer, T. Frauenheim
Alkane Assembly and Diffusion at Gold Electrodes
Molecular assembly and patterning are important for future electronics, e.g. “soft” lithography. In an EU integrate project, NaPa, large scale classical simulation of alkanethiol assembly are being undertaken to understand the assembly of these species at gold electrodes.
The diffusion and spreading of alkanethiol ink molecules has been investigated using million atom simulations. During the simulation, the defect present in the alkanethiol monolayer heals and the in molecules diffuse over the monolayer surface. An ink molecule near the defect becomes trapped, preventing spreading.
Publication
J PHYS CHEM B 112 8906 8911 2008 Guanidinium Chloride Molecular Diffusion in Aqueous and Mixed Water−Ethanol Solutions G. Gannon, J.A. Larsson, J.C. Greer, D. Thompson
For
further information and to discuss your requirements please
contact:
Dr. Jim Greer at +353 (0)21 4904345 and jim.greer@tyndall.ie
|
|
|
Programme Coordinator: Paul Roseingrave | Telephone:
+353 (0)21 490 4268 | Email: nap@tyndall.ie
|
|
|
|
