metals - Find the spectral distribution of a metallic reflection given electron configuration

If I have the electron configuration for a metallic element, how do I find the spectral distribution of its specular reflection?

For example, for gold (2,8,18,32,18,1) I should get a greater distribution in longer wavelengths.

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Since this is for programming purposes, a rough estimate is okay, although the ability to input alloys would be even better.