LaFeSi2 crystallizes in the orthorhombic Cmcm space group. La(1) is bonded in a 14-coordinate geometry to four equivalent Fe(1), four equivalent Si(1), and six equivalent Si(2) atoms. Fe(1) is bonded in a 4-coordinate geometry to four equivalent La(1) and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to four equivalent La(1), four equivalent Fe(1), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent La(1), one Si(1), and two equivalent Si(2) atoms.
LaFeSi2 crystallizes in the orthorhombic Cmcm space group. La(1) is bonded in a 14-coordinate geometry to four equivalent Fe(1), four equivalent Si(1), and six equivalent Si(2) atoms. There are two shorter (3.16 Å) and two longer (3.19 Å) La(1)-Fe(1) bond lengths. All La(1)-Si(1) bond lengths are 3.23 Å. There are four shorter (3.15 Å) and two longer (3.25 Å) La(1)-Si(2) bond lengths. Fe(1) is bonded in a 4-coordinate geometry to four equivalent La(1) and four equivalent Si(1) atoms. There are two shorter (2.25 Å) and two longer (2.31 Å) Fe(1)-Si(1) bond lengths. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to four equivalent La(1), four equivalent Fe(1), and one Si(2) atom. The Si(1)-Si(2) bond length is 2.64 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent La(1), one Si(1), and two equivalent Si(2) atoms. Both Si(2)-Si(2) bond lengths are 2.40 Å.