SiO2 Boisen M B, Gibbs G V, Bukowinski M S T Physics and Chemistry of Minerals 21 (1994) 269-284 Framework silica structures generated using simulated annealing with a potential energy function based on an H6Si2O7 molecule Sample: 5 _database_code_amcsd 0007870 4.9329 4.9329 6.4645 90 90 90 P4_32_12 atom x y z Si .81770 .81771 .5 O .26834 .36457 .80193