SiO2 crystallizes in the monoclinic Cc space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), 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 distorted bent 150 degrees geometry to two equivalent Si(2) atoms. 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 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom.
SiO2 crystallizes in the monoclinic Cc space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(3) bond length is 1.61 Å. The Si(1)-O(4) bond length is 1.63 Å. Both Si(1)-O(2) bond lengths are 1.62 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 1.61 Å. The Si(2)-O(4) bond length is 1.63 Å. There is one shorter (1.62 Å) and one longer (1.63 Å) Si(2)-O(1) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Si(2) atoms. 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 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom.