Abstract for the Fourth Foresight Conference on Molecular Nanotechnology.

Design of Basic Elements of Molecular Computers Based on Quantum Mechanical Investigation of Photoactive Supermolecules, Supramolecules and Small Fullerene Molecules

Dr. Arvydas Tamulis (a)E. Stumbrys (*) 9(b) V. Tamulis (**) (c) J. Tamuliene

Dr. Arvydas Tamulis
Institute of Theoretical
Physics and Astronomy
A. Gostauto, Vilnius 2600, Lithuania
E-mail: Arvydas.Tamulis@itpa.fi.lt (INTERNET)
Fax: (370-2)-224694 and (370-2)-225361
Phones: (370-2)-620861 and (370-2)-778743
A. Tamulis, E. Stumbrys (*), V. Tamulis (**) J. Tamuliene Institute of Theoretical Physics and Astronomy, A.Gostauto 12
2600 Vilnius, Lithuania; Phones: (370-2)620861, (370-2)778743
fax:(370-2)225361, (370-2)224694; e-mail:Arvydas.Tamulis@itpa.fi.lt
Vilnius University, Faculties of Physics (*), Sauletekio 9
III rumai, 2054 Vilnius,;e-mail: uo02@.ltvucc11.vm.vu.lt and
Biology (**),M. K. Ciurlionio str., Vilnius, Lithuania

Quantum mechanical investigations of stability of empty fullerene $C_{20}$, $C_{24}$, $C_{26}$, $C_{28}$, $C_{30}$, $C_{32}$, $C_{34}$, $C_{36}$, $C_{38}$, $C_{40}$, $C_{42}$, $C_{44}$, $C_{46}$, $C_{48}$, $C_{50}$, $C_{52}$ molecules isomers with highest symmetry and endohedral fullerene molecules with the same cage and encapsulated even valence atoms Be, C, O, Mg, Si, S, Zn, Ge, Se, Cd, Sn, Te, Hg, Pb or odd valence atoms H, N, F, Al, P, Cl, Ga, As, Br, In, Sb, I, Tl, Bi inside were performed using point set group theory in the framework of semiempirical MOPAC-PM3 method. The main criterion of stability of calculated empty or endohedral fullerene molecules we state that their highest occupied molecular orbital (HOMO) must be completely electron filled - without free valences. We have found that empty $C_{24}$, $C_{26}$, $C_{32}$ ($D_{3h}$ isomer), $C_{34}$ ($D_{6h}$), $C_{42}$ ($D_{3}$), $C_{44}$ (T), $C_{46}$ ($C_{3}$ isomer), $C_{48}$ ($D_{6d}$), $C_{50}$ ($D_{5h}$) molecules are stable. We state that completely filled HOMO endohedral fullerene molecules which posses positive energy of formation (i.e. difference between total energy of endohedral fullerene molecule and the sum of total energies of corresponding empty fullerene molecule and encapsulated atom) must be most stable. They are: Be@$C_{24}$, Ga@$C_{24}$, In@$C_{34}$, Si@$C_{34}$, Ge@$C_{34}$, Be@$C_{36}$, Al@$C_{36}$, Ga@$C_{36}$, Si@$C_{36}$, Se@$C_{36}$, Te@$C_{36}$, Ge@$C_{40}$, Se@$C_{40}$, Te@$C_{40}$, Ga@$C_{42}$, In@$C_{42}$, Si@$C_{42}$, Se@$C_{42}$, Te@$C_{42}$, Se@$C_{46}$, Te@$C_{46}$, Si@$C_{48}$, Ge@$C_{48}$, Se@$C_{48}$, Te@$C_{48}$, Si@$C_{50}$, Se@$C_{50}$, Te@$C_{50}$, Se@$C_{52}$ and Te@$C_{52}$. 136 completely filled HOMO endohedral fullerene molecules which posses negative energy of formation we have found to be metastable. Several metastable endohedral fullerene molecules after additional optimization of geometry becomes as stable. They are: Si@$C_{30}$, Si@$C_{32}$, Br@$C_{36}$, Te@$C_{36}$, Ge@$C_{42}$. The stability of twenty eight photoactive charge transfer supramolecules constructed from disc-like pentayne (pentakis(phenylethynyl)phenyl) molecules with radicals R = -O$C_{5}$$H_{11}$,-C$H_{3}$,-C$F_{3}$,-CN and seven organic electron acceptor molecules was investigated calculated using MOPAC-PM3 method. Energies of formation are largest for supramolecules constructed from disc-like pentayne with -CH radical and 2,4,5,7-tetranitro-9-fluorenone (TeNF) or 2,4,5,7-tetranitro-9-dicyano-fluorene (TeN9$(CN)_{2}$F) molecules. The optimization of molecules orientation and mutual distances in supramolecules were done. Molecules TeNF, TeN9$(CN)_{2}$F and 2,4,5-trinitro-9-dicyano-fluorene (TNF) are oriented approximately by the same way relative pentayne molecule with radical -C$H_{3}$. The intermolecule bond orders in supramolecules were examined. The strongest interactions occurs in supramolecules: TNF::pentayne with radical -O$C_{5}$$H_{11}$, TeClBQ::pentayne with radical -O$C_{5}$$H_{11}$, TNF::pentayne with radical -C$H_{3}$, TeN9$(CN)_{2}$F::pentayne with radical -C$H_{3}$, TeNF::pentayne with radical -C$H_{3}$. It was founded atoms and fragments of molecules which are responsible for the large values of intermolecular bond orders, i. e. self-assembly and formation of appropriate supramolecules. Molecular implementation of two, three and four variable logic function devices, molecular implementation of summators, variable resistors of neuromolecular networks and cells of quantum cellular automata were designed based on results of MOPAC quantum chemical calculations of photodonor, insulator, acceptor, empty fullerene $C_{60}$, $C_{28}$$H_{4}$ $C_{20}$$H_{6}$ and endohedral fullerene A@$C_{60}$ molecules [1,2]. Complete set of sixteen molecular implementation of two variable logic functions is proposed using molecular implementation of two variable molecular logic function initial basic sets: {OR, AND, NEGATION} or {NOR}, or/and {NAND} [1,2].