“…small molecule organic materials without an inversion centre (Horiuchi & Tokura, 2008). Among these materials, glycinium phosphite, NH 3 CH 2 COOHÁ-H 2 PO 3 (GPI), is one of the most extensively studied crystalline compounds as a result of its ferroelectric, piezoelectric and also nonlinear optical properties (Tchukvinskyi et al, 1998;Wiesner, 2003;Krishnan et al, 2018). At room temperature, the material crystallizes in the centrosymmetric monoclinic space group P2 1 /a (Averbuch-Pouchot, 1993;Shikanai et al, 2003) and stays paraelectric down to 225 K. Cooling below 224-225 K results in a phase transition into a low-temperature ferroelectric phase (Dacko et al, 1996;Tchukvinskyi et al, 1998).…”