A robust algorithm is presented that determines the symmetries present in an atomic con®guration and idealizes the cell parameters according to the crystal system suggested by the symmetries detected. No information besides the coordinates of the atoms within some arbitrary unit cell of the crystal is required.

An important part of the crystallographic description of crystal structures, whether they belong to synthesized compounds or have been generated by computer, is the assignment of the correct space group. Since this task often proves to be highly nontrivial, we have developed an algorithm which determines the space group and the transformation to the standard setting of a given crystal structure, where no restrictions are placed on the original description of the structure.

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We present extensive numerical investigations of the structural relaxation dynamics of a realistic model of the amorphous high-temperature ceramic a-Si3B3N7, probing the mean-square displacement of the atoms, the bond survival probability, the average energy, the specific heat, and the two-point energy average. Combining the information from these different sources, we identify a transition temperature Tc approximately 2000 K below which the system is no longer ergodic and physical quantities observed over a time t(obs) show a systematic parametric dependence on the waiting time t(w), or age, elapsed after the quench. The aging dynamics "stiffens" as the system becomes older, which is similar to the behavior of highly idealized models such as Ising spin glasses and Lennard-Jones glasses.