Molecular dynamics simulations for a fluorozirconate glass (55ZrF(4). 17BaF(2). 5EuF(3). 23NaF in mol %) have been carried out in order to investigate a mechanism of a peculiar high-pressure behavior in the permanent densification of fluorozirconate glasses, which was found by experiments recently. Simulation conditions mimic experimental ones; compression of the glass under constant pressures at a high temperature, quenching under constant pressures P-q, and then decompression (release of pressure) at constant temperatures T-d. The dependence of density on the quenching pressure P-q exhibits a maximum, which was also manifested in the experimental study. A mechanism of this peculiar densification behavior is proposed in terms of structural relaxation in the F- coordination environments around the network modifying ions (Ba2+ and Na+) during the decompression process. The "fragile" nature of fluorozirconate glasses plays an important role in this mechanism. (C) 2000 American Institute of Physics. [S0021-9606(00)70107-3].