Fluctuating charge model simulations of the order-disorder phase transition in solid NaNO_2
Abstract
We present molecular dynamics simulations of the order-disorder phase transition in solid NaNO_2. The crystal potential surface is constructed by phab initio Hartree-Fock calculations, compared to that obtained from using the Gordon-Kim electron gas theory. We find a remarkable intramolecular charge-transfer effect in response to changes in the environment of the nitrite anion. To account for such a crystal effect, we propose a polarizable-ion model in which the atomic charges in the nitrite molecule are allowed to fluctuate in the way governed by electronegativity equalization. Our numerics shows that the ferroelectric-paraelectric phase transition in solid NaNO2 is triggered by rotation of the nitrite ions around the crystallographical c axis, in agreement with recent X-ray experiments.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARS21009Y