Abstract
We have calculated the inter band absorption of potassium and sodium by means of a KKR-Z pseudopotential1,2 obtained from a fit to the experimental Fermi surface data. Previous calculations of the optical properties of the alkali metals have relied either on a local pseudopotential3 or else introduced non-locality as arising solely from the corrections due to the atomic core.4 However, it has been demonstrated that the local pseudopotential formulation5 is inadequate to account for the measured Fermi surface of K. It has also been shown6 that the pseudopotential that appears in the optical matrix element will incorporate the effects of many-body correlations only if it is consistent with the experimental data of Fermi surface measurements (such as dHvA results). The method used here was applied with this requirement being satisfied. Recent theoretical results6 and the successful application of a phenomenological model for the optical properties of Aℓ7 suggest that a one-electron potential which has been fitted to the experimental Fermi surface should implicitly contain electron-electron effects in the optical absorption. The measurement of the inter-band absorption of the alkalis, although difficult to carry out, is nevertheless of some importance as the absorption depends critically on the pseudopotential.
This work was sponsored by the Department of the Air Force.
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References
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A major contribution to the volume integral comes from the matrix element \(\left\langle {\overrightarrow k + {{\overrightarrow G }_{110}}\left| \Gamma \right|\overrightarrow k } \right\rangle\) in the direction of backscattering \(\cos {\theta _{\overrightarrow k ,\overrightarrow k + {{\overrightarrow G }_{110}}}} = \pi .\). The value of the corresponding matrix element in Lee’s calculation10 is about the same as ours. We would consequently expect that the optical absorption in K calculated by the two methods be similar.
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© 1971 Plenum Press, New York
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Wilson, A.R., Dresselhaus, G., Young, CY. (1971). Optical Properties of the Alkalis Using the KKR-Z Method. In: Marcus, P.M., Janak, J.F., Williams, A.R. (eds) Computational Methods in Band Theory. The IBM Research Symposia Series. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-1890-3_18
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DOI: https://doi.org/10.1007/978-1-4684-1890-3_18
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