SiO2 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form corner-sharing SiO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Si(2) atoms.
SiO2 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. Both Si(1)-O(1) bond lengths are 1.63 Å. Both Si(1)-O(2) bond lengths are 1.66 Å. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form corner-sharing SiO4 tetrahedra. The Si(2)-O(3) bond length is 1.63 Å. The Si(2)-O(4) bond length is 1.62 Å. Both Si(2)-O(1) bond lengths are 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Si(2) atoms.