First-principles calculations of the electronic band structure and lattice dynamics were carried out and found to be in excellent agreement with inelastic neutron scattering measurements. The numerical results revealed that the E2g in-plane B phonons near to the zone center were very anharmonic and strongly coupled to the planar B σ-bands near to the Fermi level. This giant anharmonicity and non-linear electron-phonon coupling was key to explaining quantitatively the observed high TC and B isotope effect.

Giant Anharmonicity and Nonlinear Electron-Phonon Coupling in MgB2 - a Combined First-Principles Calculation and Neutron Scattering Study. T.Yildirim, O.Gulseren, J.W.Lynn, C.M.Brown, T.J.Udovic, Q.Huang, N.Rogado, K.A.Regan, M.A.Hayward, J.S.Slusky, T.He, M.K.Haas, P.Khalifah, K.Inumaru, R.J.Cava: Physical Review Letters, 2001, 87[3], 037001 (3pp)