Objectives: Reliable computational methods to predict new solids with desired mechanical properties, metallic character, and enhanced electron-phonon coupling for superconductivity.

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Objectives Reliable computational methods to
predict new solids with desired mechanical
properties, metallic character, and enhanced
electron-phonon coupling for superconductivity. Ap
proach Simulations using the pseudopotential
density functional SIESTA code, coupled with
tight-binding and other codes Previous work We
have shown that solids can be formed from
C28-derived molecules and predicted the
properties of doped systems. Solid C28H4 is found
to bind weakly and exhibits many of the
electronic structure features of solid C60.
Chemical doping is feasible, and we predict that
the increased electron-phonon coupling leads to
superconducting transition temperatures exceeding
those of the alkali-doped C60 solids. (N. A.
Romero, J. Kim and R.M Martin, Phys. Rev. B, 70
140504, 2004.) New Results We have shown that
strongly bound solids formed from the reactive
C28 molecule can be doped and the states near the
Fermi energy acts very much as in molecular
solids. This opens the possibility of
molecular-like doping and superconductivity in a
strong covalently bonded solid. Chemical doping
is feasible, and electron phonon interactions are
large. However, structures investigated so far
show distortions that reduce the metallic
conductivity.
Larger context New routes to materials with
mechanical strength of diamond, dopable to be
good metals, and superconductors with high
transition temperatures. Development of codes
for computational materials science. Training of
students in basic science and applications.