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Groizard T, Kahlal S, Halet JF. Zwitterionic Mixed-Valence Species for the Design of Neutral Clocked Molecular Quantum-Dot Cellular Automata. Inorg Chem 2020; 59:15772-15779. [PMID: 33074686 DOI: 10.1021/acs.inorgchem.0c02207] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mixed-valence compounds can be used for the design of molecular quantum-dot cellular automata (QCA). Here, we investigate the QCA properties of a three-dot "Y"-shaped functionalized zwitterionic neutral closo-carborane model 1-(3,5-{Cp(dHpe)Fe-C≡C-}2(C6H3))-10-Cp(dHpe)Fe-C≡C-closo-1-CB9H8 (1) (Cp = cyclopentadienyl (η5-C5H5) and dHpe = 1,2-bis(phosphino)ethane (H2PCH2CH2PH2)) as a neutral clocked molecular half-cell. DFT results clearly demonstrate that 1 can display simultaneously the two most basic properties necessary for clocked QCA operation, i.e., bistable switching behavior and clocked control. This is possible due to the three stable states (two active and one null) of 1, corresponding to occupation of each of the three iron-ethynyl groups by the positive charge. In addition, the proximal electronic bias effects can be overcome by the zwitterionic nature of 1, which could be imposed by external counterions, rendering these effects more predictable.
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Affiliation(s)
- Thomas Groizard
- Univ Rennes, CNRS, Institut des Sciences Chimiques de Rennes (ISCR) - UMR 6226, F-35000 Rennes, France
| | - Samia Kahlal
- Univ Rennes, CNRS, Institut des Sciences Chimiques de Rennes (ISCR) - UMR 6226, F-35000 Rennes, France
| | - Jean-François Halet
- Univ Rennes, CNRS, Institut des Sciences Chimiques de Rennes (ISCR) - UMR 6226, F-35000 Rennes, France
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Tahara K, Terashita N, Tokunaga K, Yabumoto S, Kikuchi JI, Ozawa Y, Abe M. Zwitterionic Mixed Valence: Internalizing Counteranions into a Biferrocenium Framework toward Molecular Expression of Half-Cells in Quantum Cellular Automata. Chemistry 2019; 25:13728-13738. [PMID: 31376186 DOI: 10.1002/chem.201902840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/26/2019] [Indexed: 01/26/2023]
Abstract
Realization of molecular quantum cellular automata (QCA), a promising architecture for molecular computing through current-free processes, requires improved understanding and application of mixed-valence (MV) molecules. In this report, we present an electrostatic approach to creating MV subspecies through internalizing opposite charges in close proximity to MV ionic moieties. This approach is demonstrated by unsymmetrically attaching a charge-responsive boron substituent to a well-known organometallic MV complex, biferrocenium. Guest anions (CN- and F- ) bind to the Lewis acidic boron center, leading to unusual blue-shifts of the intervalence charge-transfer (IVCT) bands. To the best of our knowledge, this is the first reported example of a zwitterionic MV series in which the degree of positive charge delocalization can be varied by changing the bound anions, and serves to clarify the interplay between IVCT parameters. The key underlying factor is the variable zero-level energy difference in the MV states. This work provides new insight into imbuing MV molecules with external charge-responsiveness, a prerequisite of molecular QCA techniques.
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Affiliation(s)
- Keishiro Tahara
- Department of Material Science, Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo, 678-1297, Japan
| | - Nazuna Terashita
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0192, Japan
| | - Ken Tokunaga
- Division of Liberal Arts, Centre for Promotion of Higher Education, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo, 192-0015, Japan
| | - Shiomi Yabumoto
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0192, Japan
| | - Jun-Ichi Kikuchi
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0192, Japan
| | - Yoshiki Ozawa
- Department of Material Science, Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo, 678-1297, Japan
| | - Masaaki Abe
- Department of Material Science, Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo, 678-1297, Japan
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Santana-Bonilla A, Medrano Sandonas L, Gutierrez R, Cuniberti G. Exploring the write-in process in molecular quantum cellular automata: a combined modelingand first-principle approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:405502. [PMID: 31195387 DOI: 10.1088/1361-648x/ab29c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The molecular quantum cellular automata paradigm (m-QCA) offers a promising alternative framework to current CMOS implementations. A crucial aspect for implementing this technology concerns the construction of a device which effectively controls intramolecular charge-transfer processes. Tentative experimental implementations have been developed in which a voltage drop is created generating the forces that drive a molecule into a logic state. However, important factors such as the electric field profile, its possible time-dependency and the influence of temperature in the overall success of charge-transfer are relevant issues to be considered in the design of a reliable device. In this work, we theoretically study the role played by these processes in the overall intramolecular charge-transfer process. We have used a Landau-Zener (LZ) model, where different time-dependent electric field profiles have been simulated. The results have been further corroborated employing density functional tight-binding method. The role played by the nuclear motions in the electron-transfer process has been investigated beyond the Born-Oppenheimer approximation by computing the effect of the external electric field in the behavior of the potential energy surface. Hence, we demonstrate that the intramolecular charge-transfer process is a direct consequence of the coherent LZ nonadiabatic tunneling and the hybridization of the diabatic vibronic states which effectively reduces the trapping of the itinerant electron at the donor group.
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Affiliation(s)
- Alejandro Santana-Bonilla
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, 01062 Dresden, Germany. Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
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Rahimi E, Reimers JR. Molecular quantum cellular automata cell design trade-offs: latching vs. power dissipation. Phys Chem Chem Phys 2018; 20:17881-17888. [PMID: 29924110 DOI: 10.1039/c8cp02886a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The use of molecules to enact quantum cellular automata (QCA) cells has been proposed as a new way for performing electronic logic operations at sub-nm dimensions. A key question that arises concerns whether chemical or physical processes are to be exploited. The use of chemical reactions allows the state of a switch element to be latched in molecular form, making the output of a cell independent of its inputs, but costs energy to do the reaction. Alternatively, if purely electronic polarization is manipulated then no internal latching occurs, but no power is dissipated provided the fields from the inputs change slowly compared to the molecular response times. How these scenarios pan out is discussed by considering calculated properties of the 1,4-diallylbutane cation, a species often used as a paradigm for molecular electronic switching. Utilized are results from different calculation approaches that depict the ion either as a charge-localized mixed-valence compound functioning as a bistable switch, or else as an extremely polarizable molecule with a delocalized electronic structure. Practical schemes for using molecular cells in QCA and other devices emerge.
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Affiliation(s)
- Ehsan Rahimi
- Faculty of Electrical and Robotic Engineering, Shahrood University of Technology, Shahrood, Iran.
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Fresch B, Bocquel J, Rogge S, Levine RD, Remacle F. A Probabilistic Finite State Logic Machine Realized Experimentally on a Single Dopant Atom. NANO LETTERS 2017; 17:1846-1852. [PMID: 28211693 DOI: 10.1021/acs.nanolett.6b05149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Exploiting the potential of nanoscale devices for logic processing requires the implementation of computing functionalities departing from the conventional switching paradigm. We report on the design and the experimental realization of a probabilistic finite state machine in a single phosphorus donor atom placed in a silicon matrix electrically addressed and probed by scanning tunneling spectroscopy (STS). The single atom logic unit simulates the flow of visitors in a maze whose topology is determined by the dynamics of the electronic transport through the states of the dopant. By considering the simplest case of a unique charge state for which three electronic states can be resolved, we demonstrate an efficient solution of the following problem: in a maze of four connected rooms, what is the optimal combination of door opening rates in order to maximize the time that visitors spend in one specific chamber? The implementation takes advantage of the stochastic nature of electron tunneling, while the output remains the macroscopic current whose reading can be realized with standard techniques and does not require single electron sensitivity.
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Affiliation(s)
- Barbara Fresch
- Department of Chemistry, B6c, University of Liege , B4000 Liege, Belgium
- Department of Chemical Science, University of Padova , Via Marzolo 1, 35131 Padova, Italy
| | - Juanita Bocquel
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Sven Rogge
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - R D Levine
- The Fritz Haber Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
- Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine and Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States
| | - F Remacle
- Department of Chemistry, B6c, University of Liege , B4000 Liege, Belgium
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