SiO2 is High (Orthorhombic) Tridymite-like structured and crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms.
SiO2 is High (Orthorhombic) Tridymite-like structured and crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.61 Å. Both Si(1)-O(2) bond lengths are 1.61 Å. In the second Si site, Si(2) is bonded to two equivalent O(4) and two equivalent O(5) atoms to form corner-sharing SiO4 tetrahedra. Both Si(2)-O(4) bond lengths are 1.60 Å. Both Si(2)-O(5) bond lengths are 1.60 Å. In the third Si site, Si(3) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. Both Si(3)-O(3) bond lengths are 1.61 Å. Both Si(3)-O(4) bond lengths are 1.60 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms.