Theoretical modeling and simulation of electron-phonon scattering processes in molecular electronic devices

Alessio GagliardiPaderborn, Univ., Diss., 200

IETS and quantum interference: propensity rules in the presence of an interference feature

Destructive quantum interference in single molecule electronics is an intriguing phe- nomenon; however, distinguishing quantum interference effects from generically low transmission is not trivial. In this paper, we discuss how quantum interference ef- fects in the transmission lead to either low current or a particular line shape in current-voltage curves, depending on the position of the interference feature. Sec- ondly, we consider how inelastic electron tunneling spectroscopy can be used to probe the presence of an interference feature by identifying vibrational modes that are se- lectively suppressed when quantum interference effects dominate. That is, we expand the understanding of propensity rules in inelastic electron tunneling spectroscopy to molecules with destructive quantum interference.Comment: 19 pages, 6 figure

Modeling and Analysis of 802.11p Physical Layer for V2X Connected Transport Systems Considering Harsh Operating Conditions and HW Device Performance

Intelligent driving is a promising area for increased safety and comfort. Vehicular communication is an essential part to build such systems. This paper describes the modelling and the implementation of the IEEE 802.11p Physical (PHY) Layer to determine its reliability for vehicle-to-everything (V2X), and particularly vehicle-to-vehicle (V2V), communications in the automotive field. A Matlab/Simulink simulation is carried out to analyze not only the baseband processing of the transceiver, but also the RF hardware part, the physical channel in different operating conditions and environments, and all the main impairments and sources of interferences/noise. The transceiver model consists of three parts, the transmitter, the receiver and the intermediate channel block. The model can be used to explore the performance (bit-rate, successfully delivered packet-rate, latency,..) of V2X links in different conditions (line-of-sight, non-line-of-sight), and environments (urban, suburban, rural and highway), considering single-hop or multi-hop networking, and allowing also dynamically changing the channel characteristics, or even using different modulation and coding schemes and physical transmission parameters. To assess the proposed V2X simulation tool, the simulation results are compared to the theoretical performance and to experimental results, obtained using the NEC LinkBird-MX C2X device. The proposed simulation tool can be useful to study the impact of vehicles distance, speed and operating scenario on the reliability of the communication system, once fixed the hardware apparatus, or to specify the performance of the hardware components needed to ensure a given V2X communication performance

Single-molecule Electronics: Cooling Individual Vibrational Modes by the Tunneling Current

Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes, can in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular 'heat sink' where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the 'cooling mode', given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions, have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.Comment: 18 pages, 6 figure

O corporativismo da Itália fascista entre palavras e realidade

It is common knowledge that State intervention in Italy in the Twenties and the Thirties developed outside of corporative institutions. The history of Fascist corporatism, however, is not only an unsuccessful story. Despite the failure of the “corporatist revolution” and “Fascist third way”, Fascist corporatism since the mid-Twenties helped the progressive development of a new political system to regulate relationship between State and private interests. The paper examines not only the institutional framework (the systems of formal laws, regulations, and procedures, and informal norms) but also their acts and real activities. It dwells upon internal debates, political and institutional importance acquired by corporative institutions in Fascist regime and behaviours of entrepreneurial organizations and labour unions. In this way, the paper aims to point out the “real” consequences of Fascist corporatism, different from the ideological ones.Es de conocimiento común que la intervención del Estado en Italia en los años 1920 y 1930 se desarrolló a partir de las instituciones corporativas. La historia del corporativismo fascista, sin embargo, no es del todo sin éxito. A pesar del fracaso de la “revolución corporativista” y de la “tercera vía fascista”, el corporativismo fascista desde mediados de la década de 1920 ayudó al desarrollo progresivo de un nuevo sistema político para regular la relación entre los intereses públicos y privados. En este artículo se examina no sólo el marco institucional (los sistemas de derecho formales, reglamentos, procedimientos y reglas informales), sino también a sus actividades y acciones reales. Este trabajo se ocupa de debates internos, importancia política e institucional adquiridos por las entidades corporativas en los regímenes y el comportamiento de las organizaciones empresariales y de los sindicatos fascistas. Por lo tanto, este artículo pretende poner de manifiesto las consecuencias “reales” del corporativismo fascista, a diferencia de las consecuencias ideológicas.É de conhecimento geral que intervenções estatais na Itália nas décadas de 1920 e 1930 se desenvolveram fora de instituições corporativas. A história do corporativismo fascista, no entanto, não é totalmente sem sucessos. Apesar da falha da “revolução corporativista” e da “terceira via fascista”, o corporativismo fascista, desde meados dos anos 1920, ajudou no desenvolvimento progressivo de um novo sistema político para regular a relação entre o Estado e interesses privados. O presente artigo examina não apenas a arcabouço institucional (os sistemas de leis formais, regulamentações, procedimentos e normas informais), mas também suas atividades reais e atos. Esse trabalho aborda debates internos, importância política e institucional adquirida por instituições corporativas em regimes fascistas e comportamentos de organizações empreendedoras e sindicatos trabalhistas. Dessa forma, este artigo visa ressaltar as consequências “reais” do corporativismo fascista, diferente das ideológicas