Molecular Electronics

Gold nanoparticles protected by a binary mixture of thiolate molecules have a ligand shell that can spontaneously separate into nanoscale domains. Complex morphologies arise in such ligand shells, including striped, patchy, and Janus domains. Characterization of these morphologies remains a challenge. Scanning tunneling microscopy (STM) imaging has been one of the key approaches to determine these structures, yet the imaging of nanoparticles' surfaces faces difficulty stemming from steep surface curvature, complex molecular structures, and the possibility of imaging artifacts in the same size range. Images obtained to date have lacked molecular resolution, and only domains have been resolved. There is a clear need for images that resolve the molecular arrangement that leads to domain formation on the ligand shell of these particles. Herein we report an advance in the STM imaging of gold nanoparticles, revealing some of the molecules that constitute the domains in striped and Janus gold nanoparticles. We analyze the images to determine molecular arrangements on parts of the particles, highlight molecular "defects" present in the ligand shell, show persistence of the features across subsequent images, and observe the transition from quasimolecular to domain resolution. The ability to resolve single molecules in the ligand shell of nanoparticles could lead to a more comprehensive understanding of the role of the ligand structure in determining the properties of mixed-monolayer-protected gold nanoparticles.

Mind<>Computer: Attempts to mimic human intelligence through methods of classical computing have failed because implementing basic elements of rationality has proven obstinate to the design criterion of machine intelligence. A radical definition of Consciousness describing awareness, as the dynamic representation of a noumenon comprised of three base states; and not itself fundamental as generally defined in the current reductionistic view of the standard model, which has created an intractable hard problem of consciousness as defined by Chalmers. By clarifying the definition of matter a broader ontological quantum theory removes immateriality from the Cartesian split bringing mind into the physical realm for pragmatic investigation. Evidence suggests that the brain is a naturally occurring quantum computer, but the brain not being paramount to awareness does not itself evanesce consciousness without the interaction of a nonlocal conscious process; because Mind <> computer and cannot be reduced to brain states alone. The proposed cosmology of consciousness is indicative of a teleological principle as an inherent part of a conscious universe. By applying the parameters of quantum brain dynamics to the stack of a specialized hybrid electronic optical quantum computer with a heterosoric molecular crystal core, consciousness evanesces through entrainment of the non local conscious processes. This 'extracellular containment of natural intelligence' probably represents the only viable direction for AI to simulate 'conscious computing' because true consciousness = life.

Mutagenesis studies have been used to investigate the role of a heme ligand containing protein loop (67-79) in the activation of diheme peroxidases. Two mutant forms of the cytochrome c peroxidase of Pseudomonas aeruginosa have been produced. One mutant (loop mutant) is devoid of the protein loop and the other (H71G) contains a non-ligating Gly at the normal histidine ligand site. Spectroscopic data show that in both mutants the distal histidine ligand of the peroxidatic heme in the un-activated enzyme is lost or is exchangeable. The un-activated H71G and loop mutants show, respectively, 75% and 10% of turnover activity of the wild-type enzyme in the activated form, in the presence of hydrogen peroxide and the physiological electron donor cytochrome c 551. Both mutant proteins show the presence of constitutive reactivity with peroxide in the normally inactive, fully oxidised, form of the enzyme and produce a radical intermediate. The radical product of the constitutive peroxide reaction appears to be located at different sites in the two mutant proteins. These results show that the loss of the histidine ligand from the peroxidatic heme is, in itself, sufficient to produce peroxidatic activity by providing a peroxide binding site and that the formation of radical intermediates is very sensitive to changes in protein structure. Overall, these data are consistent with a major role for the protein loop 67-79 in the activation of di-heme peroxidases and suggest a ''charge hopping'' mechanism may be operative in the process of intra-molecular electron transfer.

We use a combination of first principles many-body methods and the numerical renormalizationgroup technique to study the Kondo regime of cobalt-porphyrin compounds adsorbed on a Cu surface. We find the Kondo temperature to be highly sensitive to both molecule charging and distance to the surface, which can explain the variations observed in recent scanning tunneling spectroscopy measurements. We discuss the importance of many-body effects in the molecular electronic structure controlling this phenomenon and suggest scenarios where enhanced temperatures can be achieved in experiments.

Mind<>Computer: Attempts to mimic human intelligence through methods of classical computing have failed because implementing basic elements of rationality has proven obstinate to the design criterion of machine intelligence. A radical definition of Consciousness describing awareness, as the dynamic representation of a noumenon comprised of three base states; and not itself fundamental as generally defined in the current reductionistic view of the standard model, which has created an intractable hard problem of consciousness as defined by Chalmers. By clarifying the definition of matter a broader ontological quantum theory removes immateriality from the Cartesian split bringing mind into the physical realm for pragmatic investigation. Evidence suggests that the brain is a naturally occurring quantum computer, but the brain not being paramount to awareness does not itself evanesce consciousness without the interaction of a nonlocal conscious process; because Mind <> computer and cannot be reduced to brain states alone. The proposed cosmology of consciousness is indicative of a teleological principle as an inherent part of a conscious universe. By applying the parameters of quantum brain dynamics to the stack of a specialized hybrid electronic optical quantum computer with a heterosoric molecular crystal core, consciousness evanesces through entrainment of the non local conscious processes. This 'extracellular containment of natural intelligence' probably represents the only viable direction for AI to simulate 'conscious computing' because true consciousness = life.

The challenge of realizing electronic devices based on organic materials started in the early 70‟s. The discovery and advent of conducting polymers in the 80‟s paved the way to new solution-based process and realization of cheap and flexible electronic devices. Mastering thin films fabrication by evaporation techniques also made possible devices realization with optimal properties and control. Organic electronics is nowadays becoming a mainstream innovative field, with perspectives in solar cells, lightning and cheap electronics. The first industrial products are emerging in our every day‟s life, for example in screens for portable electronics. From another perspective, electrical transport through molecules, or entities of molecular size or thickness, created a growing interest in the research community. The development has been slower, mostly hindered by the technical issue of matching the nm molecular size with the typical 100 nm electrical interconnects sizes. This is illustrated by the scientific literature on the topic, with large fractions of the publications related to theoretical studies and nanofabrication methodologies, leaving aside only a marginal numbers of experimental results reports. The field of molecular electronics has nevertheless matured, and initial high expectations are nowadays moderated by the reality of difficulties in reuniting the molecular and macroscopic worlds. In particular, the scanning probe studies on molecules deposited on surfaces illustrated that stability usually require cryogenic temperatures, and the intrinsic conductivity of the molecules under study can be remarkably modified by the environment, the molecules conformations, and details of its interactions with the substrate. These points illustrate how difficult it is to create molecular devices of reproducible and robust properties. Tackling molecular electronics problems through size reduction of „standard‟ organic electronics systems also have stringent limits. The progress in this field cannot be compared to progress in miniaturization of inorganic silicon-based electronics. The primary technical bottleneck to miniaturization is metal-organic interfaces, which have a large importance for organic devices, and easily become predominant for sub-micrometer sizes. A huge research effort has been dedicated to this problem in the last 15 years, aiming at better for better characterization and understanding of dielectric-organic and metal-organic interfaces joining two materials of very different electronic properties. In the midway between bulk organic electronics and single molecule devices, are molecular electronic devices in the size range of 10-100 nm. This thesis is mostly dedicated to investigate these intermediate size devices. We envision several key advantages: (1) direct top-down nanofabrication tools can be used to fabricate reliable and reproducible interconnects in the 50 – 100 nm size range, (2) we can use bottom up fabrication methodologies to create molecular-based materials of size exceeding a few tens of nanometers, (3) by targeting devices where transport occurs though a significant number of molecules, we get access to average properties, with the advantage of studying more robust and reproducible samples, with expected environmental stability making ambient conditions measurements possible. Our ambition is to convince the reader that this mid-sized devices approach is promising, with high potentials. Our ambition is to provide a solid ground for molecular electronics devices realization, where reliability and results confidence are priorities. This explains why, all along this thesis, a large number of control experiments have been performed. This thesis is essentially articulated in three sections. In the first section (Chapter II), we present our methodology for creating the electrodes circuit, the interconnects, the excitation and measurement environments. Light is used as a trigger or excitation source, illustrating how molecular devices can have controlled properties, making them potential candidates for devices properties beyond those of standard inorganic electronics. For this aim, the setup for electrical measurements is placed in a home built-interconnect setup over an inverted optical microscope where we can apply simultaneous optical-electrical measurements followed by temperature and magnetic field complementary studies. We report the fabrication of lateral electrodes with high aspect ratio (104) separated by a 20-100 nm distance, and using simple optical lithography techniques. These „nanotrenches‟ are our basic top-down tool for interfacing organic materials. The next section (Chapter III) is a proof-of-principle experiment, showing that we can create robust molecular electronics devices. The best experimental confirmation for the occurrence of molecular-type transport relates to the study of „switching‟ molecules. Such systems exhibit a reversible, and possibly hysteretic, modification of their properties under external stimulus. For experimental convenience reasons, aiming at minimizing the risks of experimental artifacts, we use a benchmark molecular system, choosing a photochromic molecular film. These molecules are known to reversibly exhibit a change of conformation (cis↔trans) under light excitations in the UV and blue ranges. We use a microsphere coated with a film of these molecules, and trapped over the nanotrench. The sphere is the intermediate size connector, closing the junction between metallic electrodes through a double molecular layer. While a light induced change of conduction has been shown in a vertical geometry in these molecules, the lateral geometry is unexplored. On-switching molecular films as check system, we provide quantitative success rate in observing electrical transport unambiguously related to molecules properties, reaching a success rate better than 90%. The third section (chapters IV and V) presents the use of our methodology to investigate original new molecular materials. The spincrossover phenomenon, occurring as a collective transition with hysteretic behavior triggered by a change in temperature, pressure or irradiation in transition metal complexes, from paramagnetic high spin state (HS, S=2) to diamagnetic low spin state (LS, S=0) has been studied thoroughly in the literature, and well suites as switching molecular system. The transition is often accompanied by a change in color, dielectric constant and volume of the bulk material. Studies have shown that due to the collective nature of the transition, the hysteresis occurs in an ensemble of molecules and not in single molecules, thus spincrossover nanostructures are ideal candidates for observing the physical change (volume) due to the transition and we aimed to detect this change in their transport properties in chapter IV. We therefore used original spin crossover nanoparticles, of well-characterized spin transition properties, positioned over 100 nm-size gaps. The obtained results do not relate to spin transition, but to other intrinsic properties of the particles (high conductivity and photoconductivity) and confirmed that this geometry and size scale opens a view to novel properties investigation. The other molecular system is designed for supramolecular electronics studies, where the bottom-up fabrication involves the construction of a large molecular architecture, of size matching the nanotrenches widths. We investigate a self-assembled molecular system based on a triarylamine derivative as building block. Light triggers a polymerization of these molecules, through radicals creation in the solution. When this growth procedure is probed between metallic electrodes, a surprising self-fabrication of highly conductive molecular wires parallel to the linesof electric field in the gap is observed. The wires have an ohmic character with conductivity values of 104 S.m-1 combined with an extremely low interface resistance, typically six orders of magnitude lower than conventional polymers, samples exhibit high environmental stability persisting for a long time. This "discovery‟, detailed in chapter V, represents a milestone discovery for organic electronics since it describes the first molecular self-assembly having intrinsic metallic behavior in both bulk and at the metal/organic interface when lowering the temperature down to 1.5 K. Once again we emphasize the importance of the intermediate sized devices in making progress in the field of molecular electronics, by discovering materials with novel intrinsic properties and taking a great step towards lowering the parasitic interface resistance of organic materials with metals using self-fabrication procedures.

An implicit split-operator FFT algorithm for the numerical solution of the time-dependent Schrodinger equation is implemented for the electronic structure of H q and and H . The covalent versus separated-atoms behavior is described by two 2 2

We present an experimental study of charge transport through single oligo(phenylene-ethynylene) (OPE3) molecules and anthracene substituted OPE3 (OPE3-AC) contacted with a mechanically controlled break junction. Both molecules are measured using two different methods. In the first approach, we measure the low-bias conductance, while the junction is repeatedly broken and fused. In the second approach, instead of applying a fixed bias, we record current-voltage characteristics. For both approaches the data is fitted to a model describing transport through a single level, and information about the level alignment and the electronic coupling to the electrodes is extracted. We find that the electronic coupling is similar for both molecules, but that the level alignment differs. The observed trends are confirmed by quantum chemistry calculations.

Recent experiments have demonstrated that the electron transmission yield through chiral molecules depends on the electron spin orientation. This phenomenon has been termed the chiral-induced spin selectivity (CISS) effect, and it provides a challenge to theory and promise for organic molecule-based spintronic devices. This article reviews recent developments in our understanding of CISS. Different theoretical models have been used to describe the effect; however, they all presume an unusually large spin-orbit coupling in chiral molecules for the effect to display the magnitudes seen in experiments. A simplified model for an electron&#39;s transport through a chiral potential suggests that these large couplings can be manifested. Techniques for measuring spin-selective electron transport through molecules are overviewed, and some examples of recent experiments are described. Finally, we present results obtained by studying several systems, and we describe the possible application of...

Fabrication of electrodes with a controlled nanometric separation is strategic for many application fields as molecular electronics and biosensors. A technological process at room temperature with an high yield can be defined starting from electromigration induced break junction technique (EIBJ). A self assembly adhesion molecule (MPTMS (3-mercaptopropyl)trimethoxysilane) for gold, efficiently used in previous works, solves the problems of metallic residuals, typical of titanium and chromium. As a consequence a simple and low cost technological process to realise gold nanogaps at room temperature becomes feasible. The analysis of internal mechanisms that act on metal wire, when the density produces electromigration, together with a thermal model of the wire itself, can be used to control nanogap dimension. The design of a large set of wires, where different geometries are used to modify their thermal behaviour during electromigration, is used to verify feedback algorithms to control applied bias voltage. Some interesting experimental results seem to confirm the model proposed by the authors, opening new opportunities for future high yield nanogap fabrication.

molecular velocities and discusses the change in velocity distribution with temperature. He describes the relation of heat capacity ratio to molecular complexity, discusses isothermal and adiabatic expansion, explains the variation of pressure with altitude, and outlines Perrin's historic work on sedimentation gradients in 1910. The chapter ends with 22 good exercises for bright students. The third chapter deals with real gases. Major topics include the van der Waals equation (1881), the relation of the van der Waals parameters to the coordinates of the critical point, the law of rectilinear diameter (1886), the reduced equation of state, virial equations of state, the Berthelot equation, Joule-Thomson expansion, the liquefaction of gases, transport phenomena, mean free path, and the determination of molecular diameters from viscosity. There are 11 good exercises at the end of this chapter. In t.he last, of the four chapters kinetic theory concepts are applied to liquids, solids, and solutions. Major topics include Raoult's law and regular solutions. Exclusive of a good index, this little book contains only 98 pages of textual matter. This is 11 pages less than the average for the seven preceding volumes in the series. A few typographical errors were overlooked in proofreading but they are not the serious kind that preclude reader comprehension.

A description of the ab initio quantum chemistry package GAMESS is presented. Chemical systems containing atoms through radon can be treated with wave functions ranging from the simplest closed-shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication. Emphasis is given to novel features of the program. The parallelization strategy used in the RHF, ROHF, UHF, and GVB sections of the program is described, and detailed speecup results are given. Parallel calculations can be run on ordinary workstations as well as dedicated parallel machines. © John Wiley & Sons, Inc.

The possibility of using single molecules as active elements of electronic devices offers a variety of scientific and technological opportunities. In this article, we discuss transistors, where electrons flow through discrete quantum states of a single molecule. First, we will describe molecules, where current flows through one cobalt atom surrounded by two insulating terpyridyl ligands. Depending on the length of the insulating part of the molecules, two different behaviors are observed: Coulomb blockade for a longer molecule and the Kondo effect for a shorter molecule. We will also discuss measurements of the C fullerene and its 70 dimer (C ). In C devices, the transport measurements are affected by an intercage vibrational mode that has an energy of 11 140 140 meV. We observe a large current increase when this mode is excited, indicating a strong coupling between the electronic and mechanical degrees of freedom in C molecules.

This review presents an overview of 1 / 2 branched dendrimers and dendrons, created by a divergent procedure, from their synthesis to modern day applications. The first members of this branched class of fractal macromolecules were prepared through a cascade synthesis, which was later replaced by the iterative divergent synthetic approach. Most classes of this 1 / 2 N-, Aryl-, C-, Si-, and P-branched families are included and catalogued by their mode of connectivity. Dendritic macromolecules have had significant impact in the field of material sciences and are one of the major starting points for nanotechnology as a result of the numerous modifications that can be conducted, either on the surface or within their molecular infrastructure, thus taking advantage of their unimolecular micelle properties. These host cavities, maintained by the dendritic branches, allow for the incorporation of nanoparticles as well as metal particles, which make these attractive in catalysis and imaging studies. The solubility of these fractal constructs can be tailored depending on their surface modifications. Highly water-soluble, neutral dendrimers appended with, grown from, or acting as hosts to specific molecules give rise to a wide variety of biomedical applications such as drug delivery systems and MRI imaging agents. The inherent supramolecular or supramacromolecular chemistry has been exploited but the design and construction of uniquely tailored macrostructures have just begun. Laser dyes, as well as electron and energy donor and acceptor functionality, have also been paired with these fractal constructs in order to probe their uses in the field of molecular electronics. With their synthetic control, seemingly limitless modifications and wide variety of potential applications, as well as their now commercial availability, these 1 / 2 branched dendrimers have become an important nanostructured tools for diverse utilitarian applications. This review mainly covers 1 / 2 branched non-chiral dendrimers prepared by a divergent process but selected chiral surfaces are considered as well as metal encapsulation and a few hyperbranched routes to related imperfect dendrimers.

In molecular electronics, single molecules are stretched between two electrodes to form an electrically conducting element in which molecular conductivity is then measured. [48] This paper is a key step to make semiconducting layered materials available for printed, flexible and wearable electronics, and yet again pushes forward the state of the art." [47] An international team with ties to UCF has cracked a challenge that could herald a new era of ultra-high-density computing. [46] Researchers at New York University and IBM Research have demonstrated a new mechanism involving electron motion in magnetic materials that points to new ways to potentially enhance data storage. [45] A team of researchers at UCLA has set a new record for preparing and measuring the quantum bits, or qubits, inside of a quantum computer without error. [44]

Carbon nanotubes have unique properties that make them a most promising system on which to base molecular electronics. We briefly review the electrical characteristics of carbon nanotubes, and then focus on carbon nanotube field-effect transistors (CNT-FETs). Procedures by which hole-transport, electron-transport and ambipolar CNTFETs can be fabricated are presented, and their electrical characteristics are discussed and compared with those of Si MOSFETs. Ways to fabricate arrays of CNTFETs are also demonstrated, and electron and hole CNTFETs are integrated to form complementary logic circuits.

The charge transport through a single ruthenium atom clamped by two terpyridine hinges is investigated, both experimentally and theoretically. The metal-bis(terpyridyl) core is equipped with rigid, conjugated linkers of para-acetyl-mercapto phenylacetylene to establish electrical contact in a two-terminal configuration using Au electrodes. The structure of the [Ru II (L) 2 ](PF 6 ) 2 molecule is determined using single-crystal X-ray crystallography, which yields good agreement with calculations based on density functional theory (DFT). By means of the mechanically controllable break-junction technique, current-voltage (I-V), characteristics of [Ru II (L) 2 ](PF 6 ) 2 are acquired on a single-molecule level under ultra-high vacuum (UHV) conditions at various temperatures. These results are compared to ab initio transport calculations based on DFT. The simulations show that the cardan-joint structural element of the molecule controls the magnitude of the current. Moreover, the fluctuations in the cardan angle leave the positions of steps in the I-V curve largely invariant. As a consequence, the experimental I-V characteristics exhibit lowest-unoccupied-molecular-orbit-based conductance peaks at particular voltages, which are also found to be temperature independent.

A formalism is presented for the calculation of relativistic corrections to molecular electronic energies and properties. After a discussion of the Dirac and Breit equations and their first-order Foldy-Wouthuysen ͓Phys. Rev. 78, 29 ͑1950͔͒ transformation, we construct a second-quantization electronic Hamiltonian, valid for all values of the fine-structure constant ␣. The resulting ␣-dependent Hamiltonian is then used to set up a perturbation theory in orders of ␣ 2 , using the general framework of time-independent response theory, in the same manner as for geometrical and magnetic perturbations. Explicit expressions are given to second order in ␣ 2 for the Hartree-Fock model. However, since all relativistic considerations are contained in the ␣-dependent Hamiltonian operator rather than in the wave function, the same approach may be used for other wave-function models, following the general procedure of response theory. In particular, by constructing a variational Lagrangian using the ␣-dependent electronic Hamiltonian, relativistic corrections can be calculated for nonvariational methods as well.

Mind<>Computer: Attempts to mimic human intelligence through methods of classical computing have failed because implementing basic elements of rationality has proven obstinate to the design criterion of machine intelligence. A radical definition of Consciousness describing awareness, as the dynamic representation of a noumenon comprised of three base states; and not itself fundamental as generally defined in the current reductionistic view of the standard model, which has created an intractable hard problem of consciousness as defined by Chalmers. By clarifying the definition of matter a broader ontological quantum theory removes immateriality from the Cartesian split bringing mind into the physical realm for pragmatic investigation. Evidence suggests that the brain is a naturally occurring quantum computer, but the brain not being paramount to awareness does not itself evanesce consciousness without the interaction of a nonlocal conscious process; because Mind <> computer and cannot be reduced to brain states alone. The proposed cosmology of consciousness is indicative of a teleological principle as an inherent part of a conscious universe. By applying the parameters of quantum brain dynamics to the stack of a specialized hybrid electronic optical quantum computer with a heterosoric molecular crystal core, consciousness evanesces through entrainment of the non local conscious processes. This 'extracellular containment of natural intelligence' probably represents the only viable direction for AI to simulate 'conscious computing' because true consciousness = life.

We present an overview of various aspects of the self-assembly of organic monolayers on silicon substrates for molecular electronics applications. Different chemical strategies employed for grafting the self-assembled monolayers (SAMs) of alkanes having different chain lengths on native oxide of Si or on bare Si have been reviewed. The utility of different characterization techniques in determination of the thickness, molecular ordering and orientation, surface coverage, growth kinetics and chemical composition of the SAMs has been discussed by choosing appropriate examples. The metal counterelectrodes are an integral part of SAMs for measuring their electrical properties as well as using them for molecular electronic devices. A brief discussion on the variety of options available for the deposition of metal counterelectrodes, that is, soft metal contacts, vapor deposition and soft lithography, has been presented. Various theoretical models, namely, tunneling (direct and Fowler-Nordheim), thermionic emission, Poole-Frenkel emission and hopping conduction, used for explaining the electronic transport in dielectric SAMs have been outlined and, some experimental data on alkane SAMs have been analyzed using these models. It has been found that short alkyl chains show excellent agreement with tunneling models; while more experimental data on long alkyl chains are required to understand their transport mechanism(s). Finally, the concepts and realization of various molecular electronic components, that is, diodes, resonant tunnel diodes, memories and transistors, based on appropriate architecture of SAMs comprising of alkyl chains (-molecule) and conjugated molecules (-molecule) have been presented.

This paper focuses on describing the computational chemistry software, NWChem, and its use in materials science research. The current functionalities and capabilities are outlined, as well as future features. Specific computational examples are given to show the flexibility and usefulness of NWChem to answering materials science problems.

A proposed dinitro device, Au-͑2Ј-nitro-4-ethynylphenyl-4Ј-ethynylphenyl-5Ј-nitro-1-benzene thiolate͒-Au is analyzed using a combination of density functional and Green function theories complemented with information from theoretical and experimental studies of a similar nitroamino device, Au-͑2Ј-amino-4-ethynylphenyl-4Ј-ethynylphenyl-5Ј-nitro-1-benzenethiolate͒-Au.

Quantum computers are appealing for their ability to solve some tasks much faster than their classical counterparts. It was shown in [Aspuru-Guzik et al., Science 309, 1704] that they, if available, would be able to perform the full configuration interaction (FCI) energy calculations with a polynomial scaling. This is in contrast to conventional computers where FCI scales exponentially.

The molecular geometry of cumulene chains H 2 C n H 2 have been optimized using LCAO-SCF MO method (contracted Gaussian basis set of triple zeta valence quality TZVP and the more extended Dunning's correlation consistent basis set aug-cc-PVDZ), density functional theory at different basis set levels, and the highly parametrized MNDO(PM3) method. The bond lengths have no remarkable alternation within the chain and converge to the asymptotic limit as the value of n is getting larger. The total charges calculated by Mulliken population analysis yield unrealistic values if the split valence basis set was employed. In contrast, using NBO analysis the net charges of the individual atoms converge very rapidly to their asymptotic limits with almost zero charges on central atoms. The comparison of the different basis set results to test the reliability of proton affinities calculated from the differences in molecular enthalpies of the parent chain and the corresponding anions was carried out. The increase of the number of CaC bonds in the chain decreases these differences asymptotically. The concept of 'terminal charge repulsion' is developed for the explanation of energy effects in long chains. The role of this concept in explanation of dependence of proton affinities on the chain length was discussed. The studied compounds are the best available building blocks in bimetallic compounds with useful properties in molecular electronics and nonlinear optics. q

An implicit split-operator FFT algorithm for the numerical solution of the time-dependent Schrodinger equation is implemented for the electronic structure of H q and and H . The covalent versus separated-atoms behavior is described by two 2 2

A multireference analog of the correlation consistent composite approach (MR-ccCA) based on complete active space with second-order perturbation theory (CASPT2) has been utilized in an investigation of the ground and valence excited states of C 2 , N 2 , and O 2 . The performance of different second-order multireference perturbation theory methods including second-order n-electron valence state perturbation theory, second-order multireference Møller-Plesset, and second-order generalized van Vleck perturbation theory has been analyzed as potential alternatives to CASPT2 within MR-ccCA. The MR-ccCA-P predicts spectroscopic constants with overall mean absolute deviations from experimental values of 0.0006 Å, 7.0 cm −1 , and 143 cm −1 for equilibrium bond length (r e ), harmonic frequency (ω e ), and term values (T e ), respectively, which are comparable to the predictions by more computationally costly multireference configuration interaction-based methods.

Mind<>Computer: Attempts to mimic human intelligence through methods of classical computing have failed because implementing basic elements of rationality has proven obstinate to the design criterion of machine intelligence. A radical definition of Consciousness describing awareness, as the dynamic representation of a noumenon comprised of three base states; and not itself fundamental as generally defined in the current reductionistic view of the standard model, which has created an intractable hard problem of consciousness as defined by Chalmers. By clarifying the definition of matter a broader ontological quantum theory removes immateriality from the Cartesian split bringing mind into the physical realm for pragmatic investigation. Evidence suggests that the brain is a naturally occurring quantum computer, but the brain not being paramount to awareness does not itself evanesce consciousness without the interaction of a nonlocal conscious process; because Mind <> computer and cannot be reduced to brain states alone. The proposed cosmology of consciousness is indicative of a teleological principle as an inherent part of a conscious universe. By applying the parameters of quantum brain dynamics to the stack of a specialized hybrid electronic optical quantum computer with a heterosoric molecular crystal core, consciousness evanesces through entrainment of the non local conscious processes. This 'extracellular containment of natural intelligence' probably represents the only viable direction for AI to simulate 'conscious computing' because true consciousness = life.

This tutorial outlines the basic theoretical concepts and tools which underpin the fundamentals of
phase-coherent electron transport through single molecules. The key quantity of interest is the
transmission coefficient T(E), which yields the electrical conductance, current–voltage relations, the
thermopower S and the thermoelectric figure of merit ZT of single-molecule devices. Since T(E) is
strongly affected by quantum interference (QI), three manifestations of QI in single-molecules are
discussed, namely Mach–Zehnder interferometry, Breit–Wigner resonances and Fano resonances. A simple
MATLAB code is provided, which allows the novice reader to explore QI in multi-branched
structures described by a tight-binding (Hu¨ckel) Hamiltonian. More generally, the strengths and
limitations of materials-specific transport modelling based on density functional theory are discussed.

Electronic structure in self-assembled monolayers ͑SAMs͒ of C 60 anchored 11-amino-1-undecane thiol (C 60 -11-AUT) on Au͑111͒ was studied by means of ultraviolet photoelectron spectroscopy and hybrid density functional theory calculations. Valence band features of the molecular conformation revealed the interface electronic structure to be dominated by ͑S-Au͒, localized at the thiolate anchor to Au. Formation of a localized covalent bond as a result of hybridization between N P z orbital of -NH 2 group of the thiolate SAM and the level of C 60 resulted in a symmetry change from I h in C 60 to C1 in C 60 -11-AUT SAM. Appearance of low, but finite amplitude surface electronic states of bonded C 60 , much beyond the Fermi level, ruled out Au-C 60 end group contact. The band gap E g of the SAM, determined to be 2.7 eV, was drastically reduced from the insulating alkanethiol SAMs ͑ϳ8.0 eV͒ and fell intermediate between the C 60 ground state ͑N electrons, 1.6 eV͒ and C 60 solid ͑NϮ1 electrons, 3.7 eV͒.

We have developed a controlled and highly reproducible method of making nanometer-spaced electrodes using electromigration in ambient lab conditions. This advance will make feasible single molecule measurements of macromolecules with tertiary and quaternary structures that do not survive the liquid-helium temperatures at which electromigration is typically performed. A second advance is that it yields gaps of desired tunnelling resistance, as opposed to the random formation at liquid-helium temperatures. Nanogap formation occurs through three regimes: First it evolves through a bulk-neck regime where electromigration is triggered at constant temperature, then to a few-atom regime characterized by conductance quantum plateaus and jumps, and finally to a tunnelling regime across the nanogap once the conductance falls below the conductance quantum.

A new mechanism for negative differential resistance (NDR) originating from local orbital symmetry matching between an electrode and a molecule in a single molecular electronic device is proposed and demonstrated by a joint experimental and theoretical scanning tunneling microscope study of a cobalt phthalocyanines (CoPc) molecule on a gold substrate. For two different metal tips used, Ni and W, NDR occurs only with Ni tips and shows no dependence on the geometrical shape of the tip. Calculations reveal that such a behavior is a result of local orbital symmetry matching between the Ni tip and Co atom.

Organic-based field-effect transistors ͑OFETs͒ utilize organic semiconductor materials with low electron mobilities and organic gate oxide materials with low dielectric constants. These have rendered devices with slow operating speeds and high operating voltages, compared with their inorganic silicon-based counter parts. Using a deoxyribonucleic acid ͑DNA͒-based biopolymer, derived from salmon milt and roe sac waste by-products, for the gate dielectric region, we have fabricated an OFET device that exhibits very promising current-voltage characteristics compared with using other organic-based dielectrics. With minimal optimization, using a thin film of DNA-based biopolymer as the gate insulator and pentacene as the semiconductor, we have demonstrated a bio-organic-FET, or BiOFET, in which the current was modulated over three orders of magnitude using gate voltages less than 10 V.