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Aim: Quantum chem. of insulator-metal transition.

Quantum-chemistry evidence of metallic FCC fullerite[60] under high pressure S.S.Moliver State University of Ulyanovsk, Russia. Aim: Quantum chem. of insulator-metal transition. structure model of the high-pressure FCC close packing with [ r 5 +r 5 ] contacts of unbroken C 60 s.

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Aim: Quantum chem. of insulator-metal transition.

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  1. Quantum-chemistry evidence of metallic FCC fullerite[60] under high pressureS.S.MoliverState University of Ulyanovsk, Russia Aim: Quantum chem. of insulator-metal transition. • structure model of the high-pressure FCC close packing with [r5+r5] contacts of unbroken C60s. • open-shell restricted Hartree-Fock-Roothaan method, configurations t2, t4, t6; terms. • calculations with the large-unit-cell model of the crystal. Conclusion: rapid uniform compression, faster than atomic movements performing low-dimensional topochemical polymerization, may lead to FCC Th metallic phase.

  2. R interfullerene distance governs [r5+r5]cyclo-addition. V optimizes bond angles of 4-coordi-nated atom. W adjusts [2+2] cycle. U back bond.

  3. Crystalline class Th demands to insert fullerene into cube as the emblem shows. • St.Peter & Paul’s cathedral ascends along [001]. • FCC translations are [101] etc. • All [111] coinside with C3axes of fullerene.

  4. General expression for the total-energy part Eopen=f2∑{2AJ <t′t″|g|t′t″>-AK <t′t″|g|t″t′>}+ +f2∑AI <t′t′|g|t′t′>, f=ne/2n • Selection of determinants for terms, e.g. γ=(T,1), S=1, M=0: Â{…, t2, t3β}+Â{…, t2β, t3}=(t2t3-t3t2)(β+β)(…) • Symmetrized coulomb, exchange, self-action: J=∑<t′t″|g|t′t″>/n(n-1) K=∑<t′t″|g|t″t′>/n(n-1) I=∑<t′t′|g|t′t′>/n

  5. vdW R=100% pristine fullerite • [r5+r5] R=80% our structure • [r6+r6] R=90% 1D and 2D HPHT polymers.

  6. t4: {…t6|t0a0…} → {…t4t0a2…} V=W=U=0 t2: {…t6a2t2t0…} V~0.02R

  7. Atomic shifts V are caused mainly by covalent reasons, it is stabilization of the valence angle of 4-coordinated atom at the end of r5

  8. Total energy stabilization by atomic shifts W, U is much less significant, of the order of t4 multiplet splitting

  9. Independent self-consistent calculations of total energies and molecular orbitals of closed-shell (insulator) and open-shell (metal) electron configurations.

  10. Prediction of metallicity • DFT: electron band structure and density of states are calculated self-consistently, as well as the occupation of the bands by a fixed number of electrons. It is unknown in the beginning, whether the output will be insulator or metal, and there is no independent test for both possibilities. This contradicts the DFT methodology to apply different E[n] to metals and insulators. • MO LCAO: the 0-th approximation MOs may be taken in any configuration. The choice of certain open-shell term means certain combination of determinants, so self-consistent field for metal effectively differs from that for insulator.

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