CONCLUSION
We report first-principles calculations of the electronic band structure and lattice
dynamics for the new superconductor MgB2.
The excellent agreement between
theory and our inelastic neutron scattering measurements of the phonon density of
states gives confidence that the calculations provide a sound description of the
physical properties of the system.
The numerical results reveal that the in-plane
boron phonons (with E2g symmetry) near the zone-center are very anharmonic,
and are strongly coupled to the partially occupied planar B sigma bands near the
Fermi level.
This giant anharmonicity and non-linear electron-phonon coupling is
key to explaining the observed high Tc in MgB2.