Shell-model and first-principles calculations of vibrational, structural and ferroelectric properties of KH2PO4

We develop a shell model (SM) for potassium dihydrogen phosphate (KDP) which is fitted to ab initio (AI) results that include nonlocal van der Waals corrections. The SM comprehensively tested by comparing of structural, vibrational and ferroelectric properties with AI experimental data. relaxed structural parameters are in very good agreement the available $\Gamma$-point phonons total phonon densities states (DOSs) paraelectric phases calculated developed overall corresponding also compute effective Debye temperature as function $T$ shows accordance results. Classical molecular dynamics (MD) simulations obtained show FE-PE phase transition at $\approx 360$ K remarkable MD calculations.