Si3Se is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted body-centered cubic geometry to four equivalent Si(2) and four equivalent Se(1) atoms. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Si(1) atoms. Se(1) is bonded in a body-centered cubic geometry to eight equivalent Si(1) atoms.
Si3Se is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted body-centered cubic geometry to four equivalent Si(2) and four equivalent Se(1) atoms. All Si(1)-Si(2) bond lengths are 2.78 Å. All Si(1)-Se(1) bond lengths are 2.78 Å. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Si(1) atoms. Se(1) is bonded in a body-centered cubic geometry to eight equivalent Si(1) atoms.