Experimental (IR) and theoretical (LDA) studies of the structure and vibrational-reorientational dynamics of ferroelastic 1-aminopyridinium iodide

► Structure of (1-NH2C5H5N)+I− was optimized using ADF program (LDA method). ► Discontinuous phase transition (PT) at 384 K is confirmed by IR measurements. ► Dynamics of the 1-aminopyridinium cations contribute to the PT mechanism.