We present detailed electronic structure calculations for CaFe2As2. We investigate in particular the `collapsed tetragonal and orthorhombic regions of the temperature-pressure phase diagram and find properties that distinguish CaFe2As2 from other Fe-pnictide compounds. In contrast to the tetragonal phase of other Fe-pnictides the electronic structure in the `collapsed tetragonal phase of CaFe2As2 is found to be strongly 3D. We discuss the influence of these properties on the formation of superconductivity and in particular we find evidence that both magnetic and lattice interactions may be important to the formation of superconductivity. We also find that the Local Spin Density Approximation is able to accurately predict the ordering moment in the low temperature orthorhombic phase.
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