Development of effective empirical potentials for molecular dynamics simulations of the structures and properties of boroaluminosilicate glasses

A set of empirical potentials have been developed to enable molecular dynamics simulations of oxide glasses with the most common glass formers: silica, boron and aluminum oxides. Built upon the recent borosilicate potentials, this set of partial charge effective potentials features composition dependent variable atomic charges and pairwise short range interactions that ensure high computational efficiency. They can correctly reproduce the short range structure features of boroaluminosilicate glasses including [SiO4] tetrahedral network, aluminum coordination, and, importantly, the coordination change of boron as a function of composition. By using the newly developed potentials, a series of sodium boroaluminosilicate glasses were simulated and the structures analyzed in terms of bond distance, bond angle, and coordination number, which were compared with available theoretical, simulation and experimental results. Structural analysis such as polyhedral connectivity analysis, Qn analysis, and ring size distribution were obtained to investigate the medium range structure features of these glasses. Furthermore, mechanical properties such as Young's, shear and bulk moduli were calculated and were found to be in good agreement with experimental data. The vibrational density of states was also calculated and compared with previous MD and ab initio results. The results show [3]B and [4]B had distinctive spectra features and vibrational spectra were in good agreement with earlier ab initio studies.