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We present a thorough and quantitative comparison of double-exchange modelsto experimental data on the colossal magnetoresistance manganese perovskites.Our results settle a controversy by showing that physics beyond double-exchangeis important even in La$_{0.7}$Sr$_{0.3}$MnO$_3$, which has been regarded as aconventional double-exchange system. We show that the crucial quantity forcomparisons of different calculations to each other and to data is theconduction band kinetic energy $K$, which is insensitive to the details of theband structure and can be experimentally determined from optical conductivitymeasurements. The seemingly complicated dependence of $T_c$ on the Hund'scoupling $J$ and carrier concentration $n$ is shown to reflect the variation of$K$ with $J$, $n$ and temperature. We present results for the opticalconductivity which allow interpretation of experiments and show that a featurepreviously interpreted in terms of the Hund's coupling was misidentified. Wealso correct minor errors in the phase diagram presented in previous work.Comment: 13 pages, 7 eps figure

physical review. b, condensed matter

Optical spectral weights and the ferromagnetic transition temperature of colossal-magnetoresistance manganites: Relevance of double exchange to real materials