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Trinity College Dublin

Transport properties of nanoconfined water

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Lead PI: 
Dr. Clotilde Cucinotta
Understanding the electronic transport properties of nanoconfined systems under wetting conditions isessential for many applications ranging from molecular nanojunctions to nanoelectronics.In this project we focus on the finite bias transport properties of water in different phases confined at the interface with gold and graphene. To this end we will perform a number of combined DFT based static and dynamicalcalculations and quantum transport simulations. These will be at the level of the nonequilibriumGreen function method, as implemented in SMEAGOL code [1]. We will first address the fundamental question of the length scale under which the coherent tunnelling regime is dominant over ionic transport. Wewill calculate the dependence of the conductance in liquid water on the separation between the confiningsurfaces. Electron transport will be evaluated over a representative number of configurations extracted from a50 ps long ab-initio molecular dynamical simulation, performed using the Quantum-Espressosuite of programs. The effect of an electric field on water distribution and, correspondingly, on theconductance will be also considered. Within the tunnelling regime we will study the dependence of transportproperties of the nanoconfined system on the specific phase of water, also comparing it with thetransport in vacuum. We will explore different Auelectrodes/Ice interfaces, obtained by using differentphases and orientations for the Ice. The dependence will be explained further in terms of the complex bandstructure of the Ice moiety, which determines together with the interface structure the decay of theconductance with thickness. This study will allow us to unravel the relationship between conductance andthe microscopic structure of nanoconfined water and will provide an useful tool to detect the phase of awater sample by current measurements.[1] A.R. Rocha et al., Physical Review B. 73, 085414 (2006)Íž 17:
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