M. M. Ossowski

Molecular dynamics simulation of phase transition in AgNO3

Structural phase transition in AgN03 at high temperature is simulated by molecular dynamics. The simulations are based on the potentials calculated from the Gordon-Kim modified electron-gas formalism extended to molecular ionic crystals. AgN03 transforms into rhombohedral structure at high temperature and the phase transition is associated with the rotations of the N03 ions and displacements of the N03 and Ag ions.

High-temperature phase transition in TlN3

Abstract The phase transition in TlN 3 is simulated based on the potentials calculated from the Gordon-Kim modified electron gas model extended to ion molecular crystals. It is found that TlN 3 transforms into a cubic CsCl structure at high temperature due to the rotations of the N 3 ions. Above the phase transition the orientations of the N 3 − ions are random with four preferred orientations with respect to the cubic axes.

Simulation of structural transformation in aragonite CaCo3

The structural transformation in aragonite CaCO3 is simulated by molecular dynamics. The simulations are based on the potentials calculated from the Gordon-Kim modified electron gas formalism. We found two phase transitions in aragonite at high temperature.

Structural transitions in NaCN and KCN

An account is presented of our studies of the order-disorder phase transitions in NaCN and KCN. These are based on parameter-free inter-ionic potentials based on the Gordon-Kim modified electron gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and reproduced two transitions known in each of these systems. We also calculated upper bounds to the barrier of rotation of a cyanide ion in a ground state of NaCN and KCN and discuss possible shortcomings of our model.