Investigation of Molecular FCN for Beyond-CMOS: Technology, design, and modeling for nanocomputing

L'abstract è presente nell'allegato / the abstract is in the attachmen

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

Molecular Field-Coupled Nanocomputing (FCN) is a computational paradigm promising high-frequency information elaboration at ambient temperature. This work proposes a model to evaluate the signal energy involved in propagating and elaborating the information. It splits the evaluation into several energy contributions calculated with closed-form expressions without computationally expensive calculation. The essential features of the 1,4-diallylbutane cation are evaluated with Density Functional Theory (DFT) and used in the model to evaluate circuit energy. This model enables understanding the information propagation mechanism in the FCN paradigm based on monostable molecules. We use the model to verify the bistable factor theory, describing the information propagation in molecular FCN based on monostable molecules, analyzed so far only from an electrostatic standpoint. Finally, the model is integrated into the SCERPA tool and used to quantify the information encoding stability and possible memory effects. The obtained results are consistent with state-of-the-art considerations and comparable with DFT calculation

Robustness of the In-Plane Data Crossing for Molecular Field-Coupled Nanocomputing

Molecular Field-Coupled Nanocomputing (molFCN) offers several advantages compared to other beyond-CMOS technologies, such as the cut of the power dissipation, thanks to the absence of charge transport, and the possibility to work at room temperature. Several circuits have been investigated for molFCN, primarily analyzed from a behavioral standpoint. Also, researchers proposed a few solutions to cross two signals and analyzed them from a logical and ideal perspective. Crossing information is an essential and delicate operation since molFCN is an in-plane technology. Besides, previous works demonstrated the need to consider molecule physics to predict the behavior of a molFCN circuit. This work examines different implementations of the in-plane information crossing interconnection, considering the punctual molecule physics to predict the interconnection functioning. We tune the electrostatic feature of the involved molecules to determine the robustness of the cross-wire against static electrostatic variations, thus providing valuable information for the synthesis of ad-hoc molecules for molFCN

SCERPA: a Self-Consistent Algorithm for the Evaluation of the Information Propagation in Molecular Field-Coupled Nanocomputing

Among the emerging technologies that are intended to outperform the current CMOS technology, the field-coupled nanocomputing (FCN) paradigm is one of the most promising. The molecular quantum-dot cellular automata (MQCA) has been proposed as possible FCN implementation for the expected very high device density and possible room temperature operations. The digital computation is performed via electrostatic interactions among nearby molecular cells, without the need for charge transport, extremely reducing the power dissipation. Due to the lack of mature analysis and design methods, especially from an electronics standpoint, few attempts have been made to study the behavior of logic circuits based on real molecules, and this reduces the design capability. In this article, we propose a novel algorithm, named self-consistent electrostatic potential algorithm (SCERPA), dedicated to the analysis of molecular FCN circuits. The algorithm evaluates the interaction among all molecules in the system using an iterative procedure. It exploits two optimizations modes named Interaction Radius and Active Region which reduce the computational cost of the evaluation, enabling SCERPA to support the simulation of complex molecular FCN circuits and to characterize consequentially the technology potentials. The proposed algorithm fulfills the need for modeling the molecular structures as electronic devices and provides important quantitative results to analyze the information propagation, motivating and supporting further research regarding molecular FCN circuits and eventual prototype fabrication

Investigation of Amperometric Sensing Mechanism in Gold-C60-Gold Molecular Dot

We investigate through simulations the gold–C60–gold molecular junction as a novel single-molecule amperometric gas sensor. We find it promising for NO and NO2 detection in air and at room temperature, with current variations of the order of the microampere, and presenting the potential capability of achieving the single-molecule sensitivity along with selectivity in the presence of common atmospheric gases. Furthermore, and for the first time, we investigate the current modulation mechanism due to target–sensor intermolecular interactions, providing theoretical insights into the functioning and exclusive properties of this novel device. In particular, we show and motivate the peculiar voltage-dependent response of the sensor that we relate to the distinctive mechanism of transport modulation occurring in the presence of a specific target. Finally, we discuss sensing reliability in air and the effects of probable fabrication process variability on sensing performance. Our results motivate future works on molecular dot-based chemical sensors in terms of the sensor–target exclusive interactions and detection principles, oriented to device-level engineering to find optimal operating conditions

Ab initio Molecular Dynamics Simulations of Field-Coupled Nanocomputing Molecules

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

A Roadmap for Molecular Field-Coupled Nanocomputing Actualization

In molecular field-coupled nanocomputing, electrostatically-coupled molecules encode the logic information in their charge distribution, promising extremely low power consumption, room temperature operation, and THz frequency operations. Besides the impressive theoretical predictions and simulation confirmations, a working prototype must still be fabricated. This work discusses the most crucial aspects that hinder the fabrication of a working prototype and defines a roadmap to address and guide the procedure to fabricate a working proof of concept. Accurate physical simulations support each point of the roadmap

Public engagement in urban innovation: towards the concept of inclusive mobility

In the process towards smart city, the concept of public transportation has evolved as a set of socio-material entanglements by highlighting the social impacts. This research offers a community-based approach to identify criteria for the design towards inclusive mobility by setting a validation model to measure and extract collected stakeholders’ data. The study provides a thematization of optimizing strategies to address mobility in future smart city actions towards sustainable community development, aiming to inspire further research in Italy and beyond