Nanoforum - Nanotech Regulatory Document Archive

Details on the current research activities at the Institute of Theoretical Physics
and Astronomy:
Quantum Mechanical Investigations of Electronic Structure, Spectra, Electron Charge
and Spin Density Transfer and Magnetically Features of Organic Molecules Suitable for
Digital and Quantum Information Processing
Arvydas Tamulis, Jelena Tamuliene, Vykintas Tamulis, Aiste Ziriakoviene
Quantum mechanically designed hardware of molecular electronics digital computers
and molecular NMR and ESR quantum computers are presented. Maximal lengths of
these molecular electronics digital and quantum information processing logic gates are
no more than four nanometers and maximal width 2.5 nm.
There are presented several two and three variable gates of molecular electronics digital
computers. The results of light induced internal molecular motions in azo-dyes
molecules [1-3] have been used for the design of light driven logically controlled (OR,
AND, NOR, NAND) molecular machines composed from organic photoactive electron
donor dithieno [3,2-b: 2', 3'-d] thiophene, tetrathiofulvalene (TTF) or ferrocene
molecules and electron accepting 4,5-dinitro-9- (dicyanomethylidene)-fluorene (DN9
(CN) 2F), tetracyano-indane, and moving azo-benzene fragment. After detail
investigations of various electron insulator bridges between electrondonor and
electronacceptor parts occurs that non-conjugated bridge -CH2-CH2- should be applied
to join thiophene and DO3 molecules in order to design OR logical function that
significantly improved quality in comparison with our previous designed devices [1-3].
Density functional theory (DFT) B3PW91/6-311G model calculations were performed
for the geometry optimisation of these molecular electronics logical gates. Applied DFT
time dependent (DFT-TD/B3PW91) method and our visualization
Program give absorption spectra of designed molecular gates and show from which
fragments electrons are hopping in various excited states. There are designed set of
single supermolecule fluorescencing devices containing OR and AND logic functions.
There are presented quantum mechanical investigations of hydrogen and nitrogen atom
Nuclear Magnetic Resonance (NMR) values of Cu, Co, Zn, Mn and Fe biliverdin
derivatives and their dimers and aza-fullerene C48N12 adducts using Hartree-Fock
(HF). There are also DFT methods indicating that these modified derivatives should
generate from one to seven and eleven, twelve, eighteen, nineteen Quantum Bits
(QuBits). The chemical shifts are obtained as the difference of the values of the
tetramethylsilane (Si(CH3) 4) and ammonia (NH3) molecule Gauge-Independent Atomic
Orbital (GIAO) nuclear magnetic shielding tensor on the hydrogen and nitrogen
atoms and that of the magnetically active molecules. There are designed several single
supermolecule and supramolecular devices containing molecular electronics digital logic
gates, photoactive molecular machines and elements of molecular NMR quantum
computers that allowed to design several supramolecular ControlNOT NMR quantum
computing gates and induced idea of molecular quantum computing life.
Implementation of the quantum information processing based on spatially localised
electronic spins in stable molecular radicals is discussed. The necessary operating
conditions for such molecules are formulated in self-assembled monolayer (SAM)
systems: 1) a tailoring group, to be attached to a substrate; 2) a localised unpaired
electron spin; 3) a noncompensated chemical bond, responsible for an unpaired spin
must be strong enough. We suggest to use the neutral radical molecules with Shift
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