Ab initio Molecular Dynamics Simulations of Field-Coupled Nanocomputing Molecules

Abstract

Molecular Field-Coupled Nanocomputing (FCN) represents one of the most promising solutions to overcome the issues introduced by CMOS scaling. It encodes the information in the molecule charge distribution and propagates it through electrostatic intermolecular interaction. The need for charge transport is overcome, hugely reducing power dissipation.At the current state-of-the-art, the analysis of molecular FCN is mostly based on quantum mechanics techniques, or ab initio evaluated transcharacteristics. In all the cases, studies mainly consider the position of charges/atoms to be fixed. In a realistic situation, the position of atoms, thus the geometry, is subjected to molecular vibrations. In this work, we analyse the impact of molecular vibrations on the charge distribution of the 1,4-diallyl butane. We employ Ab Initio Molecular Dynamics to provide qualitative and quantitative results which describe the effects of temperature and electric fields on molecule charge distribution, taking into account the effects of molecular vibrations. The molecules are studied at near-absolute zero, cryogenic and ambient temperature conditions, showing promising results which proceed towards the assessment of the molecular FCN technology as a possible candidate for future low-power digital electronics. From a modelling perspective, the diallyl butane demonstrates good robustness against molecular vibrations, further confirming the possibility to use static transcharacteristics to analyse molecular circuits.

Impact of Molecular Electrostatics on Field-Coupled Nanocomputing and Quantum-Dot Cellular Automata Circuits

“…As Figure 1b shows, the molecules belonging to the same cell exhibit two opposite dipole moments (µ 1 and µ 2 ), mimicking the presence of the two charges in two of the four quantum-dots of QCA cells and encoding the logical states '0' and '1'. By using molecules to implement the paradigm, we gain two more advantages: the possibility to build very small devices [7] and the possibility to work at room temperature [18]. As Figure 1b shows, besides the basic implementation of the two logic states, a third state named 'NULL' is used to encode no information.…”

“…The integration of molecule time evolution in SCERPA enabling the evaluation of circuit transients is still under development. Nevertheless, some work started with the modeling of molecule dynamics based on time-dependent ab initio calculation [18]. QCADesigner also integrates a Graphical User Interface (GUI), which makes simple the handling of the circuit drawing and simulation.…”

A Model for the Evaluation of Monostable Molecule Signal Energy in Molecular Field-Coupled Nanocomputing

“…We base our work on the diallylbutane molecule, shown in Figure 1c. This molecule is typically used for modeling purposes [25,26] and was recently announced as a monostable molecule [27]. Moreover, this molecule is reasonably small, facilitating Density Functional Theory (DFT) calculation, and permitting the model validation through ab initio calculation.…”