BaMnO3 is (Cubic) Perovskite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with nine equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Mn(2)O6 octahedra, and faces with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the second Ba site, Ba(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with six equivalent Mn(2)O6 octahedra, faces with eight equivalent Ba(1)O12 cuboctahedra, and faces with six equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with six equivalent Ba(1)O12 cuboctahedra, and faces with two equivalent Mn(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Mn(1) atoms. In the second O site, O(2) is bonded in a distorted L-shaped geometry to one Ba(2), three equivalent Ba(1), one Mn(1), and one Mn(2) atom.
BaMnO3 is (Cubic) Perovskite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with nine equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, faces with three equivalent Mn(2)O6 octahedra, and faces with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 10°. All Ba(1)-O(1) bond lengths are 2.92 Å. There are six shorter (2.86 Å) and three longer (2.96 Å) Ba(1)-O(2) bond lengths. In the second Ba site, Ba(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with six equivalent Mn(2)O6 octahedra, faces with eight equivalent Ba(1)O12 cuboctahedra, and faces with six equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Ba(2)-O(1) bond lengths are 2.85 Å. All Ba(2)-O(2) bond lengths are 2.93 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ba(1)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedra are not tilted. All Mn(1)-O(1) bond lengths are 1.92 Å. All Mn(1)-O(2) bond lengths are 1.92 Å. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with six equivalent Ba(1)O12 cuboctahedra, and faces with two equivalent Mn(1)O6 octahedra. All Mn(2)-O(2) bond lengths are 1.90 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Mn(1) atoms. In the second O site, O(2) is bonded in a distorted L-shaped geometry to one Ba(2), three equivalent Ba(1), one Mn(1), and one Mn(2) atom.