Absolute optical rotation of CsLiB 6 O 10

The optical rotation (OR) of CsLiB 6 O 10 (CLBO, space group ) along the a axis has been determined by the HAUP method [Kobayashi & Uesu (1983). J Appl. Cryst. 16 , 204–211] at a wavelength of 632.8 nm and by the TILTER method [Kaminsky & Glazer (1996). Ferroelectrics , 183 , 133–141] at 532 nm and 650 nm. The respective rotatory powers were found to be 17 (1), 24 (2) and 19 (2)° mm −1 . The absolute chirality has been established by comparing Bijvoet differences, { hkl } and {}, on the same crystal on which OR was measured. Atomic positions and electron density Fourier peak heights were exploited as input for semi‐empirical calculations of refractive indices and OR, using WinOPTACT [Glazer (2002). J. Appl. Cryst. 35 , 652] with only one free parameter fitted to match the average refractive index.