The heat capacity anomaly at the transition to superconductivity of the layered superconductor was compared to first-principles calculations with the Coulomb repulsion as the only parameter which was fixed to give the measured TC. The Eliashberg equations were solved for both an isotropic 1-band model and a 2-band model, with different superconducting gaps on the π-band and σ-band Fermi surfaces. The agreement with experiments was considerably better for the 2-band model than for the 1-band model.

Specific Heat of MgB2 in a One- and a Two-Band Model from First-Principles Calculations. A.A.Golubov, J.Kortus, O.V.Dolgov, O.Jepsen, Y.Kong, O.K.Andersen, B.J.Gibson, K.Ahn, R.K.Kremer: Journal of Physics - Condensed Matter, 2002, 14, 1353-60