Hydroxyl Orientation in Muscovite as Indicated by Electrostatic Energy Calculations

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Science  16 Apr 1971:
Vol. 172, Issue 3980, pp. 263-264
DOI: 10.1126/science.172.3980.263


The electrostatic energy of the 2M1 muscovite structure, KAl2(Si3Al)- O10(OH)2, has been calculated as a function of the orientation of the hydroxyl group (O-H distance = 0.97 angstrom). The minimum in the electrostatic energy occurs when the OH bond makes an angle of 18° with the cleavage plane and an angle of 31° with the b-axis (in the a-b plane), which is 2.5° away from the orientation of the transition moment as determined from infrared measurements on single crystals. If the K+ ion is excluded from the calculation, the O-H bond makes an angle of 53° with the cleavage plane. This indicates the strong influence that the interlayer cation exerts on the hydroxyl hydrogen in mica structures.