W. Smith, J. Clarke
Jun 1, 1989
Citations
1
Influential Citations
5
Citations
Journal
Journal of Chemical Physics
Abstract
Constant pressure molecular dynamics simulations have been made for a simple ionic model for crystalline potassium nitrate at several pressures and temperatures which span the known phase diagram. The nitrate ion was modeled as a rigid four‐site entity with distributed charges and a quaternion algorithm was used to solve the rotational equations of motion. Several structural features of KNO3 are reproduced in the simulations. The 300 K, 0.1 GPa aragonite‐like phase II of KNO3 has been reproduced although in the model it appears at a pressure between 1 and 2 GPa. The disordering of the nitrate orientations which occurs at high temperatures has also been observed. At 3 GPa the stable phase of the model is very similar to the recently characterized phase IV of KNO3. Spontaneous phase transitions in the simulations did not always produce well ordered structures and this appears to be a problem inherent in the method.